What is a freeze-thaw cycle in concrete?

An air freeze-thaw cycle is a calendar day on which the minimum air temperature falls to 32°F (0°C) or below and the maximum air temperature rises above 32°F (0°C). Each cycle drives water trapped in concrete's pores through a freeze-expand-thaw sequence that, repeated over years, can crack and scale an unprotected surface.

Which US city has the most freeze-thaw cycles per year?

Of the 180 cities in the SlabCalc Freeze-Thaw Index, Carson City, NV records the most air freeze-thaw cycles at a mean of 174.1 per year, a severe-severity climate for which this index recommends 6.0-8.0% entrained air in exterior concrete.

Which city in the index has the fewest freeze-thaw cycles?

Fort Lauderdale, FL records the fewest air freeze-thaw cycles in the dataset at a mean of 0 per year (none band), and does not require air-entrained concrete on climate grounds.

How many US cities require air-entrained concrete for freeze-thaw protection?

132 of the 180 cities in the index (73%) average five or more air freeze-thaw cycles per year, the threshold this index uses to flag a climate as a freezing-exposure climate. The threshold is SlabCalc's; the air content ranges it maps to are drawn from the ACI 211.1 exposure tables for 3/4 in. nominal maximum aggregate.

Why do colder cities have fewer freeze-thaw cycles than milder ones?

A freeze-thaw cycle counts how often the temperature crosses freezing, not how cold it gets. St. Paul, Minnesota records 144.5 freeze days a year but only 81.1 complete cycles, because deep-winter cities stay below freezing for weeks at a time. Carson City, Nevada records 181.6 freeze days and 174.1 cycles: the large diurnal swing of a high, dry climate thaws the surface most afternoons and refreezes it overnight. That is why the interior West, not the Upper Midwest, leads this index.

Why does air-entrained concrete resist freeze-thaw damage?

Water expands roughly 9% in volume when it freezes. Air entrainment mixes billions of microscopic, evenly spaced air voids into the paste, giving that expanding water somewhere to go instead of building up pressure inside the pore structure. Concrete without enough entrained air in a freeze-thaw climate is prone to scaling and D-cracking.

How is the SlabCalc Freeze-Thaw Index calculated?

For each city, SlabCalc pulls daily minimum and maximum temperatures from the nearest qualifying NOAA GHCN-Daily station over the 2015–2024 normal period, counts the days meeting the freeze-thaw definition in each year with at least 350 days of complete data, and averages the annual counts. Full detail is in the methodology section on this page.

The SlabCalc Freeze-Thaw Index

Name: SlabCalc Freeze-Thaw Index
Creator: SlabCalc
License: https://creativecommons.org/licenses/by/4.0/

An air freeze-thaw cycle is a calendar day on which the minimum temperature falls to 32 F (0 C) or below and the maximum temperature rises above 32 F (0 C).

SlabCalc computed a mean annual air freeze-thaw cycle count for 180 US cities from NOAA NCEI Global Historical Climatology Network - Daily (GHCN-Daily), covering the 2015–2024 normal period. No comparable national table of city-level, derived freeze-thaw cycle counts is published anywhere else — NOAA publishes the raw daily station records this index is built from, but not a synthesized per-city annual cycle count, and no other concrete-industry source runs this calculation across a comparable set of cities.

Data last updated: September 17, 2026

Key Findings

Most freeze-thaw cycles

Carson City, NV: 174.1/year

Carson City, Nevada records the most air freeze-thaw cycles of any city in the index, a severe-severity climate requiring 6.0-8.0% entrained air.

Fewest freeze-thaw cycles

Fort Lauderdale, FL: 0/year

Fort Lauderdale, Florida sees the fewest cycles in the dataset (none band).

National mean

46.5 cycles/year

Unweighted mean across all 180 cities in the index.

Cities requiring air-entrained concrete

132 of 180 (73%)

Cities averaging 5 or more air freeze-thaw cycles per year, the threshold this index uses to flag a freezing-exposure climate.

Why the Coldest Cities Are Not at the Top of This Table

The result most people find surprising is that the high-altitude interior West outranks the Upper Midwest and the Great Lakes. Carson City, Nevada records 174.1 air freeze-thaw cycles a year. St. Paul, Minnesota — a materially colder place by any ordinary measure — records 81.1.

A freeze-thaw cycle is not a measure of how cold a place gets. It counts how often the temperature crosses freezing. Deep-winter cities spend weeks at a time below 32°F: the concrete freezes in December and stays frozen, which is a single sustained freeze rather than sixty separate ones. High desert and mountain-valley cities do the opposite. Thin, dry air and clear skies produce a large diurnal swing — hard radiative cooling overnight, strong solar gain by afternoon — so the surface crosses freezing in both directions on most winter days, and on a large share of spring and autumn days too.

The freeze-days column in the table below makes this visible. St. Paul records 144.5 days a year with a freeze, against Carson City’s 181.6 — the same order of magnitude. What differs is how many of those days thaw again before midnight. Carson City converts 96% of its freeze days into complete cycles; St. Paul converts 56%. In St. Paul the slab freezes and stays frozen for weeks at a time. In Carson City it thaws again by afternoon and refreezes that night.

For a slab, the number of crossings is what matters: each one drives another expansion-and-release inside the pore structure. That is why entrained air is specified against freeze-thaw exposure rather than against winter low temperature, and why a Front Range or Great Basin driveway can scale faster than one in a city most people would call far colder.

Freeze-Thaw Cycles by City

Ranked by mean annual air freeze-thaw cycles, highest to lowest. Freeze dates are mean dates over the 2015–2024 normal period; free-season days is the mean gap between the last spring freeze and first autumn freeze.

Rank	City	State	Cycles/yr	Band	Freeze days	First freeze	Last freeze	Free-season days	Air content	Station
1	Carson City	NV	174.1	Severe	181.6	Oct 1	May 29	125	6.0-8.0%	MINDEN · 22.2 km
2	Santa Fe	NM	156.8	Severe	164.4	Oct 8	May 15	146	6.0-8.0%	SANTA FE 2 · 4.8 km
3	Cheyenne	WY	137.3	Severe	167.5	Oct 5	May 12	146	6.0-8.0%	CHEYENNE · 2.9 km
4	Fort Collins	CO	134.8	Severe	148.6	Oct 11	May 6	158	6.0-8.0%	FT COLLINS · 3.6 km
5	Colorado Springs	CO	133.9	Severe	151.1	Oct 9	May 7	155	6.0-8.0%	COLORADO SPRINGS MUNI AP · 9 km
6	Denver	CO	131.7	Severe	152.5	Oct 13	May 7	159	6.0-8.0%	DENVER-STAPLETON · 1 km
7	Aurora	CO	131.7	Severe	152.5	Oct 13	May 7	159	6.0-8.0%	DENVER-STAPLETON · 14.1 km
8	Concord	NH	120.2	Severe	155.4	Oct 8	May 7	154	6.0-8.0%	CONCORD ASOS · 5.7 km
9	Helena	MT	118.7	Severe	161	Oct 7	May 8	152	6.0-8.0%	HELENA AP ASOS · 2.6 km
10	Pierre	SD	112.9	Severe	166.7	Oct 7	May 8	152	6.0-8.0%	PIERRE RGNL AP · 2.8 km
11	Lincoln	NE	110.1	Severe	139	Oct 14	Apr 24	173	6.0-8.0%	LINCOLN AP · 8.6 km
12	Bismarck	ND	108.3	Severe	180.9	Oct 1	May 11	143	6.0-8.0%	BISMARCK · 4.9 km
13	Anchorage	AK	106.6	Severe	202	Sep 21	May 17	127	6.0-8.0%	EAGLE RVR 5 SE · 16 km
14	Montpelier	VT	99.3	Severe	163.4	Oct 9	May 12	150	6.0-8.0%	MONTPELIER AP · 6.8 km
15	Grand Rapids	MI	99	Severe	142.2	Oct 17	May 5	165	6.0-8.0%	E GRAND RAPIDS · 4.3 km
16	Sioux Falls	SD	97	Severe	153.6	Oct 11	May 2	162	6.0-8.0%	SIOUX FALLS · 5.2 km
17	Reno	NV	96.3	Severe	101.5	Oct 19	Apr 25	177	6.0-8.0%	RENO WFO · 5.1 km
18	Madison	WI	95.6	Severe	145.6	Oct 13	May 4	162	6.0-8.0%	UW ARBORETUM - MADISON · 5.2 km
19	Omaha	NE	95	Severe	129.4	Oct 22	Apr 19	186	6.0-8.0%	OMAHA EPPLEY AIRFIELD · 13.8 km
20	Spokane	WA	94.2	Severe	114.6	Oct 16	Apr 20	179	6.0-8.0%	SPOKANE FELTS FLD · 8.6 km
21	Albany	NY	93.5	Severe	125.9	Oct 19	Apr 28	174	6.0-8.0%	ALBANY INTL AP · 9.1 km
22	Topeka	KS	92.5	Severe	109.7	Oct 23	Apr 14	192	6.0-8.0%	TOPEKA ASOS · 7.4 km
23	Salt Lake City	UT	91.4	Severe	103.8	Oct 29	Apr 4	208	6.0-8.0%	SALT LAKE CITY INTL AP · 2.9 km
24	Boise	ID	91	Severe	105.6	Oct 23	Apr 22	184	6.0-8.0%	BOISE AIR TERMINAL · 3.7 km
25	Amarillo	TX	90.5	Severe	97.5	Oct 29	Apr 14	198	6.0-8.0%	AMARILLO · 11.9 km
26	Harrisburg	PA	90.3	Severe	110.8	Oct 27	Apr 17	193	6.0-8.0%	HARRISBURG 1 NE · 1.4 km
27	Augusta	ME	90.1	Severe	140.1	Oct 20	Apr 22	181	6.0-8.0%	AUGUSTA STATE AP · 5.4 km
28	Albuquerque	NM	89.4	Severe	90.7	Nov 5	Apr 5	214	6.0-8.0%	ALBUQUERQUE INTL AP · 7.5 km
29	Wichita	KS	88	Severe	100.9	Oct 27	Apr 11	199	6.0-8.0%	WICHITA · 9.5 km
30	Providence	RI	87.7	Severe	103.5	Oct 29	Apr 8	204	6.0-8.0%	PROVIDENCE · 11.2 km
31	Aurora	IL	87.6	Severe	128.1	Oct 29	Apr 24	188	6.0-8.0%	AURORA WATER · 2.4 km
32	Lansing	MI	87.6	Severe	128.7	Oct 21	Apr 29	175	6.0-8.0%	LANSING CAPITAL CITY AP · 7.6 km
33	Hartford	CT	86.9	Severe	105.6	Oct 29	Apr 12	200	6.0-8.0%	HARTFORD BRAINARD FLD · 4.2 km
34	Philadelphia	PA	86.2	Severe	98.5	Nov 4	Apr 9	209	6.0-8.0%	PENNSAUKEN 1N · 10.6 km
35	Worcester	MA	86	Severe	121.3	Oct 31	Apr 21	193	6.0-8.0%	WORCESTER · 5.4 km
36	Juneau	AK	85.5	Severe	122	Oct 3	May 2	154	6.0-8.0%	JUNEAU AP · 22.1 km
37	Fort Wayne	IN	85.4	Severe	115.5	Oct 20	Apr 26	177	6.0-8.0%	FT WAYNE INTL AP · 13.9 km
38	Cincinnati	OH	85.3	Severe	99	Oct 22	Apr 26	179	6.0-8.0%	CINCINNATI MUNI AP LUNKEN FLD · 8.6 km
39	Des Moines	IA	84.5	Severe	123.3	Oct 25	Apr 18	190	6.0-8.0%	DES MOINES INTL AP · 5.6 km
40	Columbus	OH	83.6	Severe	107	Oct 21	Apr 29	175	6.0-8.0%	COLUMBUS WCMH · 5.8 km
41	Rochester	NY	83.3	Severe	121	Oct 28	May 1	180	6.0-8.0%	ROCHESTER GTR INTL · 7.5 km
42	Springfield	IL	81.3	Severe	105.1	Oct 21	Apr 19	185	6.0-8.0%	SPRINGFIELD ABRAHAM LINCOLN CA · 6.9 km
43	St. Paul	MN	81.1	Severe	144.5	Oct 21	Apr 25	179	6.0-8.0%	ST PAUL DWTN AP · 4.2 km
44	Knoxville	TN	81.1	Severe	85.9	Oct 30	Apr 11	202	6.0-8.0%	KNOXVILLE EXP STN · 8.1 km
45	Trenton	NJ	80.3	Severe	93.1	Oct 28	Apr 11	200	6.0-8.0%	TRENTON-MERCER AP · 7.4 km
46	Toledo	OH	78.8	High	107.5	Oct 29	Apr 30	182	5.5-7.5%	TOLEDO METCALF FLD · 14.2 km
47	Overland Park	KS	77.5	High	97.8	Oct 29	Apr 10	202	5.5-7.5%	OLATHE JOHNSON CO EXECUTIVE AP · 6.1 km
48	Frankfort	KY	76.6	High	88.2	Oct 24	Apr 19	188	5.5-7.5%	FRANKFORT CAPITAL CITY AP · 3.5 km
49	Akron	OH	76.3	High	101.2	Nov 1	Apr 26	189	5.5-7.5%	AKRON FULTON INTL AP · 6.8 km
50	Minneapolis	MN	76.1	High	143.9	Oct 22	Apr 22	183	5.5-7.5%	LOWER ST ANTHONY FALLS · 2.4 km
51	Charleston	WV	76.1	High	87.5	Oct 27	Apr 21	189	5.5-7.5%	CHARLESTON - YEAGER AP · 5 km
52	Jefferson City	MO	76	High	89.6	Oct 25	Apr 14	194	5.5-7.5%	JEFFERSON CITY MEM AP · 3.4 km
53	Indianapolis	IN	75.9	High	99.1	Oct 29	Apr 17	195	5.5-7.5%	INDIANAPOLIS · 13.8 km
54	Baltimore	MD	75.5	High	82.9	Nov 1	Apr 6	209	5.5-7.5%	BALTIMORE-WASHINGTON INTL AP · 15.5 km
55	Buffalo	NY	75.1	High	113.6	Nov 1	Apr 24	191	5.5-7.5%	BUFFALO · 11.8 km
56	St. Louis	MO	74.8	High	90.6	Oct 25	Apr 11	197	5.5-7.5%	CAHOKIA ST LOUIS DWTN AP · 11.5 km
57	Milwaukee	WI	74	High	111.4	Nov 3	Apr 22	195	5.5-7.5%	MILWAUKEE MITCHELL AP · 13.1 km
58	Detroit	MI	73.7	High	105.2	Nov 3	Apr 22	195	5.5-7.5%	DETROIT CITY AP · 8.1 km
59	Pittsburgh	PA	72.9	High	97.5	Oct 26	Apr 19	190	5.5-7.5%	PITTSBURGH ALLEGHENY CO AP · 10.5 km
60	Olympia	WA	71.9	High	73.2	Oct 16	Apr 28	171	5.5-7.5%	OLYMPIA AP · 7.5 km
61	Kansas City	MO	71.7	High	89.3	Nov 2	Apr 7	209	5.5-7.5%	KANSAS CITY DWTN AP · 3.4 km
62	Boston	MA	67.4	High	84.9	Nov 10	Apr 4	220	5.5-7.5%	BOSTON · 2.5 km
63	Lexington	KY	67.3	High	80.2	Oct 28	Apr 16	195	5.5-7.5%	LEXINGTON BLUEGRASS AP · 13.4 km
64	Chicago	IL	67.2	High	97.3	Nov 6	Apr 11	209	5.5-7.5%	CHICAGO MIDWAY AP · 8.3 km
65	Dover	DE	67	High	74.4	Nov 7	Apr 1	220	5.5-7.5%	DOVER · 2.1 km
66	Oklahoma City	OK	66.1	High	72.8	Nov 4	Apr 1	217	5.5-7.5%	OKLAHOMA CY WILL ROGERS WORLD · 11.8 km
67	Newark	NJ	65.7	High	80.2	Nov 14	Apr 4	224	5.5-7.5%	HARRISON · 3.2 km
68	Jersey City	NJ	65.7	High	80.2	Nov 14	Apr 4	224	5.5-7.5%	HARRISON · 8.4 km
69	Louisville	KY	63.7	High	75.2	Oct 31	Apr 9	205	5.5-7.5%	LOUISVILLE BOWMAN FLD · 7.3 km
70	Richmond	VA	63	High	66.9	Nov 13	Apr 5	222	5.5-7.5%	RICHMOND INTL AP · 13.6 km
71	Tulsa	OK	60.6	High	66.4	Nov 9	Apr 1	222	5.5-7.5%	TULSA INTL AP · 8.2 km
72	Clarksville	TN	60.2	High	66.9	Nov 1	Apr 8	207	5.5-7.5%	CLARKSVILLE WWTP · 2.4 km
73	Newport News	VA	59.8	High	62.9	Nov 13	Apr 2	225	5.5-7.5%	NEWPORT NEWS INTL AP · 6.7 km
74	Winston-Salem	NC	56.1	High	59.5	Nov 7	Apr 2	219	5.5-7.5%	WINSTON SALEM REYNOLDS AP · 4.7 km
75	Cary	NC	54.3	High	57.4	Nov 11	Mar 31	225	5.5-7.5%	APEX · 4.5 km
76	Cleveland	OH	53.6	High	79.2	Nov 16	Apr 6	224	5.5-7.5%	CLEVELAND BURKE LAKEFRONT AP · 5.3 km
77	Greensboro	NC	51.8	High	53.4	Nov 8	Mar 28	225	5.5-7.5%	GREENSBORO WTP · 2.2 km
78	Durham	NC	51.3	High	53.9	Nov 11	Mar 31	225	5.5-7.5%	RALEIGH AP · 14.2 km
79	Nashville	TN	49.7	High	55.3	Nov 11	Mar 26	230	5.5-7.5%	NASHVILLE INTL AP · 11 km
80	Lubbock	TX	49.6	High	54.1	Nov 6	Mar 21	230	5.5-7.5%	LUBBOCK WFO · 3.9 km
81	Charlotte	NC	48.6	High	49.5	Nov 7	Mar 28	224	5.5-7.5%	CHARLOTTE DOUGLAS AP · 11.3 km
82	Eugene	OR	48.4	High	49.4	Oct 27	Mar 26	215	5.5-7.5%	EUGENE-MAHLON SWEET FLD · 11.5 km
83	Raleigh	NC	45.6	High	46.9	Nov 13	Mar 26	232	5.5-7.5%	RALEIGH STATE UNIV · 6.9 km
84	Huntsville	AL	45.6	High	47.9	Nov 10	Mar 20	235	5.5-7.5%	HUNTSVILLE INTNL AP · 11.6 km
85	New York	NY	45.4	High	57.7	Nov 19	Mar 27	237	5.5-7.5%	NY CITY CNTRL PARK · 13.2 km
86	Chattanooga	TN	43.7	Moderate	45.4	Nov 11	Mar 21	235	5.0-7.0%	CHATTANOOGA AP · 5.7 km
87	Washington	DC	43.2	Moderate	48.5	Nov 19	Mar 23	241	5.0-7.0%	WASHINGTON REAGAN NATL AP · 6.5 km
88	Virginia Beach	VA	41.9	Moderate	44.9	Nov 20	Apr 3	231	5.0-7.0%	OCEANA NAS · 4.2 km
89	Little Rock	AR	41.8	Moderate	44.7	Nov 12	Mar 15	242	5.0-7.0%	LITTLE ROCK AP ADAMS FLD · 11.2 km
90	Atlanta	GA	41.7	Moderate	42.3	Nov 11	Mar 21	235	5.0-7.0%	ATLANTA FULTON CO AP · 9.6 km
91	Salem	OR	41.7	Moderate	42.9	Nov 10	Apr 5	219	5.0-7.0%	SALEM AP (MCNARY FIELD) · 2.7 km
92	Annapolis	MD	41.6	Moderate	48	Nov 22	Mar 19	248	5.0-7.0%	ANNAPOLIS US NAVAL ACADEMY ASO · 2.5 km
93	Yonkers	NY	41.2	Moderate	51.9	Nov 26	Mar 25	246	5.0-7.0%	LAGUARDIA AP · 18.5 km
94	Augusta	GA	39.9	Moderate	40	Nov 9	Mar 23	231	5.0-7.0%	AUGUSTA BUSH FLD AP · 10.2 km
95	Fayetteville	NC	39.4	Moderate	40.3	Nov 16	Mar 20	241	5.0-7.0%	FAYETTEVILLE RGNL AP GRANNIS F · 13.4 km
96	Chesapeake	VA	38.7	Moderate	42	Nov 21	Mar 19	247	5.0-7.0%	NORFOLK S · 22.3 km
97	Frisco	TX	37.6	Moderate	40.2	Nov 12	Mar 15	242	5.0-7.0%	MCKINNEY MUNI AP · 21.9 km
98	McKinney	TX	37.6	Moderate	40.2	Nov 12	Mar 15	242	5.0-7.0%	MCKINNEY MUNI AP · 7.2 km
99	Birmingham	AL	36	Moderate	36.9	Nov 14	Mar 19	240	5.0-7.0%	BIRMINGHAM AP · 6.4 km
100	Memphis	TN	34.5	Moderate	38.6	Nov 17	Mar 12	250	5.0-7.0%	MEMPHIS INTL AP · 6.1 km
101	Norfolk	VA	33.8	Moderate	36	Oct 30	Mar 27	217	5.0-7.0%	NORFOLK NAS · 4.3 km
102	Arlington	TX	32.4	Moderate	34.5	Nov 15	Mar 6	254	5.0-7.0%	ARLINGTON MUNI AP · 5.5 km
103	Grand Prairie	TX	32.4	Moderate	34.5	Nov 15	Mar 6	254	5.0-7.0%	ARLINGTON MUNI AP · 7.6 km
104	El Paso	TX	31.2	Moderate	31.2	Nov 23	Feb 27	269	5.0-7.0%	EL PASO INTL AP · 6.4 km
105	Seattle	WA	30.3	Moderate	31.4	Nov 9	Mar 20	234	5.0-7.0%	SEATTLE BOEING FLD · 8.6 km
106	Santa Rosa	CA	28.4	Moderate	28.4	Nov 12	Mar 9	248	5.0-7.0%	SANTA ROSA SONOMA CO AP · 11.2 km
107	Plano	TX	26.7	Moderate	29.3	Nov 24	Mar 3	266	5.0-7.0%	RICHARDSON · 6.1 km
108	Garland	TX	26.7	Moderate	29.3	Nov 24	Mar 3	266	5.0-7.0%	RICHARDSON · 14.2 km
109	Vancouver	WA	26.3	Moderate	28	Nov 20	Mar 11	254	5.0-7.0%	PORTLAND INTL AP · 4.7 km
110	Columbia	SC	26	Moderate	26.3	Nov 21	Mar 11	255	5.0-7.0%	COLUMBIA OWENS DWTN AP · 11.1 km
111	Jackson	MS	25.7	Moderate	26.9	Nov 19	Mar 5	259	5.0-7.0%	JACKSON HAWKINS FLD · 2.5 km
112	Tacoma	WA	25.3	Moderate	25.9	Nov 16	Mar 11	250	5.0-7.0%	TACOMA #1 · 3.6 km
113	Montgomery	AL	24.1	Moderate	24.2	Nov 11	Feb 27	257	5.0-7.0%	MONTGOMERY 6SW · 10.9 km
114	Fort Worth	TX	23.3	Moderate	25.9	Nov 21	Feb 23	271	5.0-7.0%	FT WORTH MEACHAM FLD · 5 km
115	Columbus	GA	23.1	Moderate	23.2	Nov 20	Mar 7	258	5.0-7.0%	COLUMBUS METRO AP · 6.3 km
116	Shreveport	LA	22.4	Moderate	23.2	Nov 21	Mar 3	263	5.0-7.0%	SHREVEPORT · 5 km
117	Irving	TX	20.4	Moderate	23	Nov 26	Feb 24	275	5.0-7.0%	DAL-FTW WSCMO AP · 6.6 km
118	Dallas	TX	17.3	Low	19.6	Nov 27	Feb 19	281	4.5-6.5%	DALLAS FAA AP · 8.2 km
119	Tallahassee	FL	16.6	Low	16.6	Nov 27	Mar 7	265	4.5-6.5%	TALLAHASSEE · 9.6 km
120	Portland	OR	15.3	Low	17.5	Nov 25	Feb 28	270	4.5-6.5%	PORTLAND KGW-TV · 3.7 km
121	Stockton	CA	14.8	Low	14.8	Nov 28	Feb 11	290	4.5-6.5%	STOCKTON AP · 12 km
122	Baton Rouge	LA	13.2	Low	13.4	Nov 28	Feb 20	281	4.5-6.5%	BATON ROUGE METRO AP · 10.9 km
123	Elk Grove	CA	12.4	Low	12.4	Nov 27	Feb 13	287	4.5-6.5%	SACRAMENTO AP ASOS · 14.1 km
124	Modesto	CA	11.3	Low	11.3	Dec 1	Feb 3	301	4.5-6.5%	MODESTO AP · 4.4 km
125	Austin	TX	9.6	Low	10.7	Nov 30	Feb 16	287	4.5-6.5%	AUSTIN-CAMP MABRY · 2.5 km
126	San Antonio	TX	9.4	Low	10.1	Dec 3	Feb 18	288	4.5-6.5%	SAN ANTONIO INTL AP · 9.9 km
127	Mobile	AL	9.2	Low	9.2	Nov 28	Feb 13	288	4.5-6.5%	MOBILE DWTN AP · 7.3 km
128	Tucson	AZ	7.9	Low	7.9	Dec 2	Feb 9	296	4.5-6.5%	TUCSON INTL AP · 8.4 km
129	Mesa	AZ	7.3	Low	7.3	Dec 21	Feb 17	307	4.5-6.5%	E MESA · 7 km
130	Gilbert	AZ	7.3	Low	7.3	Dec 21	Feb 17	307	4.5-6.5%	E MESA · 15.2 km
131	Las Vegas	NV	6.6	Low	6.6	Dec 10	Jan 26	318	4.5-6.5%	LAS VEGAS AIR TERMINAL · 6.7 km
132	North Las Vegas	NV	6.6	Low	6.6	Dec 10	Jan 26	318	4.5-6.5%	LAS VEGAS AIR TERMINAL · 12.8 km
133	Houston	TX	4.2	None	4.3	Dec 3	Feb 3	303	Not required	HOUSTON WILLIAM P HOBBY AP · 18.7 km
134	Henderson	NV	4.1	None	4.1	Dec 12	Feb 2	313	Not required	MCCARRAN INTL AP · 14.1 km
135	Bakersfield	CA	3.9	None	3.9	Dec 15	Feb 1	317	Not required	BAKERSFIELD AP · 9.1 km
136	Fremont	CA	3.9	None	3.9	Dec 18	Feb 11	310	Not required	FREMONT · 8.5 km
137	Fresno	CA	3.8	None	3.8	Dec 8	Feb 2	309	Not required	FRESNO YOSEMITE INTL · 6.5 km
138	Laredo	TX	3.8	None	3.8	Dec 13	Jan 30	317	Not required	LAREDO INTL AP · 3.7 km
139	Corpus Christi	TX	3.3	None	3.6	Dec 19	Jan 29	324	Not required	C C BOTANICAL GARDENS · 24.5 km
140	Sacramento	CA	2.8	None	2.8	Dec 11	Jan 31	314	Not required	SACRAMENTO 5 ESE · 4.6 km
141	New Orleans	LA	2.2	None	2.2	Dec 3	Jan 21	316	Not required	NEW ORLEANS LAKEFRONT AP · 9.1 km
142	Scottsdale	AZ	2.2	None	2.2	Dec 23	Jan 19	338	Not required	SCOTTSDALE MUNI AP · 9.8 km
143	Phoenix	AZ	1.8	None	1.8	Dec 23	Jan 21	336	Not required	PHOENIX DEER VALLEY MUNI AP · 13.3 km
144	Peoria	AZ	1.8	None	1.8	Dec 23	Jan 21	336	Not required	PHOENIX DEER VALLEY MUNI AP · 24.8 km
145	Surprise	AZ	1.8	None	1.8	Dec 23	Jan 21	336	Not required	PHOENIX DEER VALLEY MUNI AP · 35.8 km
146	Jacksonville	FL	1.6	None	1.6	Dec 5	Jan 31	308	Not required	JACKSONVILLE NAS · 11.5 km
147	San Jose	CA	1.5	None	1.5	Dec 12	Jan 18	328	Not required	SAN JOSE · 12 km
148	Fontana	CA	1.1	None	1.1	Dec 7	Feb 4	306	Not required	ONTARIO INTL AP · 12.2 km
149	Brownsville	TX	1.1	None	1.1	Dec 23	Jan 22	335	Not required	BROWNSVILLE · 9.4 km
150	Ontario	CA	1.1	None	1.1	Dec 7	Feb 4	306	Not required	ONTARIO INTL AP · 3.1 km
151	Rancho Cucamonga	CA	1.1	None	1.1	Dec 7	Feb 4	306	Not required	ONTARIO INTL AP · 8.6 km
152	Oakland	CA	0.9	None	0.9	Dec 22	Jan 22	334	Not required	OAKLAND INTL AP · 5.8 km
153	Orlando	FL	0.5	None	0.5	Dec 24	Jan 18	340	Not required	ORLANDO INTL AP · 6.9 km
154	Tampa	FL	0.3	None	0.3	Dec 24	Jan 18	340	Not required	TAMPA INTL AP · 6 km
155	Riverside	CA	0.3	None	0.3	No freeze observed	Jan 10	365	Not required	RIVERSIDE MUNI AP · 4.2 km
156	Irvine	CA	0.3	None	0.3	Dec 28	Mar 4	299	Not required	IRVINE RCH · 6.4 km
157	Chula Vista	CA	0.3	None	0.3	Dec 27	Jan 19	342	Not required	SAN DIEGO BROWN FLD · 6.1 km
158	Santa Clarita	CA	0.3	None	0.3	Dec 28	Jan 2	360	Not required	VAN NUYS AP · 22.7 km
159	San Bernardino	CA	0.3	None	0.3	No freeze observed	Jan 10	365	Not required	RIVERSIDE MUNI AP · 24.6 km
160	Moreno Valley	CA	0.3	None	0.3	No freeze observed	Jan 10	365	Not required	RIVERSIDE MUNI AP · 21.4 km
161	Chandler	AZ	0.2	None	0.2	No freeze observed	Jan 2	365	Not required	PHOENIX AP · 21.4 km
162	Glendale	AZ	0.2	None	0.2	No freeze observed	Jan 2	365	Not required	PHOENIX AP · 20.9 km
163	Tempe	AZ	0.2	None	0.2	No freeze observed	Jan 2	365	Not required	PHOENIX AP · 8 km
164	Glendale	CA	0.2	None	0.2	Dec 28	Jan 1	361	Not required	BURBANK GLENDALE PASADENA AP · 11.2 km
165	St. Petersburg	FL	0.1	None	0.1	No freeze observed	Jan 18	365	Not required	ST PETERSBURG ALBERT WHITTED A · 1.9 km
166	Pembroke Pines	FL	0.1	None	0.1	Dec 15	No freeze observed	365	Not required	HOLLYWOOD N PERRY AP · 10 km
167	Los Angeles	CA	0	None	0	No freeze observed	No freeze observed	365	Not required	CULVER CITY · 1.6 km
168	San Diego	CA	0	None	0	No freeze observed	No freeze observed	365	Not required	SAN DIEGO MONTGOMERY FLD · 0.2 km
169	San Francisco	CA	0	None	0	No freeze observed	No freeze observed	365	Not required	SAN FRANCISCO DWTN · 53.4 km
170	Miami	FL	0	None	0	No freeze observed	No freeze observed	365	Not required	MIAMI INTL AP · 10.9 km
171	Long Beach	CA	0	None	0	No freeze observed	No freeze observed	365	Not required	LONG BEACH DAUGHERTY AP · 3.9 km
172	Honolulu	HI	0	None	0	No freeze observed	No freeze observed	365	Not required	HONOLULU INTL AP · 9.5 km
173	Anaheim	CA	0	None	0	No freeze observed	No freeze observed	365	Not required	ANAHEIM · 7.8 km
174	Santa Ana	CA	0	None	0	No freeze observed	No freeze observed	365	Not required	SANTA ANA FIRE STN · 1.7 km
175	Port St. Lucie	FL	0	None	0	No freeze observed	No freeze observed	365	Not required	STUART · 17.8 km
176	Cape Coral	FL	0	None	0	No freeze observed	No freeze observed	365	Not required	FT MYERS PAGE FLD AP · 15 km
177	Hialeah	FL	0	None	0	No freeze observed	No freeze observed	365	Not required	MIAMI OPA LOCKA AP · 4.9 km
178	Oxnard	CA	0	None	0	No freeze observed	No freeze observed	365	Not required	OXNARD VENTURA CO AP · 0.3 km
179	Huntington Beach	CA	0	None	0	No freeze observed	No freeze observed	365	Not required	SANTA ANA JOHN WAYNE AP · 12.8 km
180	Fort Lauderdale	FL	0	None	0	No freeze observed	No freeze observed	365	Not required	FT LAUDERDALE · 7 km

Freeze-Thaw Severity by State

Population-weighted mean across each state's cities in the index, ranked by cycle count.

Rank	State	Cities in index	Cycles/yr	Band
1	Wyoming (WY)	1	137.3	Severe
2	Colorado (CO)	4	132.6	Severe
3	New Hampshire (NH)	1	120.2	Severe
4	Montana (MT)	1	118.7	Severe
5	North Dakota (ND)	1	108.3	Severe
6	Alaska (AK)	2	104.5	Severe
7	Nebraska (NE)	2	100.8	Severe
8	Vermont (VT)	1	99.3	Severe
9	New Mexico (NM)	2	98.8	Severe
10	South Dakota (SD)	2	98	Severe
11	Utah (UT)	1	91.4	Severe
12	Idaho (ID)	1	91	Severe
13	Maine (ME)	1	90.1	Severe
14	Rhode Island (RI)	1	87.7	Severe
15	Connecticut (CT)	1	86.9	Severe
16	Kansas (KS)	3	85.8	Severe
17	Iowa (IA)	1	84.5	Severe
18	Pennsylvania (PA)	3	84.2	Severe
19	Wisconsin (WI)	2	81.3	Severe
20	Michigan (MI)	3	80.6	Severe
21	Minnesota (MN)	2	78.2	High
22	Indiana (IN)	2	78.1	High
23	Ohio (OH)	5	77.3	High
24	West Virginia (WV)	1	76.1	High
25	Maryland (MD)	2	73.2	High
26	Missouri (MO)	3	72.9	High
27	Massachusetts (MA)	2	71.9	High
28	Illinois (IL)	3	69	High
29	New Jersey (NJ)	3	67.6	High
30	Delaware (DE)	1	67	High
31	Kentucky (KY)	3	65.3	High
32	Oklahoma (OK)	2	64.1	High
33	North Carolina (NC)	7	49.1	High
34	Tennessee (TN)	5	48.6	High
35	New York (NY)	5	47.5	High
36	Virginia (VA)	5	46	High
37	District of Columbia (DC)	1	43.2	Moderate
38	Arkansas (AR)	1	41.8	Moderate
39	Washington (WA)	5	40.4	Moderate
40	Georgia (GA)	3	37.3	Moderate
41	Alabama (AL)	4	29.4	Moderate
42	Nevada (NV)	5	27.2	Moderate
43	Oregon (OR)	3	26.1	Moderate
44	South Carolina (SC)	1	26	Moderate
45	Mississippi (MS)	1	25.7	Moderate
46	Texas (TX)	18	17.4	Low
47	Louisiana (LA)	3	10.1	Low
48	Arizona (AZ)	10	3.3	None
49	California (CA)	28	1.7	None
50	Florida (FL)	11	1.4	None
51	Hawaii (HI)	1	0	None

What Does a Freeze-Thaw Cycle Do to Concrete?

Concrete is a porous material that holds a small percentage of free water in its capillary pores even after curing. When that water freezes, it expands by roughly 9% in volume. In concrete without enough entrained air, the expanding ice has nowhere to go, so it pressurizes the surrounding paste. A single freeze rarely does visible damage, but repeated cycles fatigue the paste, and the damage compounds every winter.

Air entrainment is the standard defense: an admixture creates billions of microscopic, closely spaced air voids throughout the paste. These voids act as relief valves — expanding water migrates into the nearest void instead of building up pressure, so the paste stays intact through the freeze-thaw cycle.

Two failure modes show up most often where air entrainment is inadequate for the local climate:

Scaling — the loss of a thin surface layer of mortar, usually starting at edges and joints and often accelerated by de-icing salts.
D-cracking — a pattern of fine cracks running parallel to joints and edges, caused by freeze-thaw damage to susceptible coarse aggregate rather than the paste itself.

ACI 318 (Building Code Requirements for Structural Concrete) sets exposure-category requirements, including air content, for concrete exposed to freezing and thawing. ACI 201.2R (Guide to Durable Concrete) covers the mechanism and mitigation of freeze-thaw deterioration in more depth. This page does not attempt to reproduce either document — consult them directly for design and code compliance.

How Should a Contractor Read This Number?

The cycles/year figure and severity band on this page map to practical decisions about air content, curing method, and when to schedule exterior pours.

Band	Cycles/yr	Curing	Pour scheduling
None	0–4.9 cycles/yr	Standard moist curing is sufficient; freeze protection is not a design driver.	Pours can be scheduled year-round without cold-weather concreting measures.
Low	5–19.9 cycles/yr	Use ACI 306-style cold-weather curing on any pour that could see a freeze before the mix reaches roughly 500 psi.	Watch the extended forecast in shoulder-season months; a single early or late freeze is the main risk.
Moderate	20–44.9 cycles/yr	Plan blanket or enclosure curing for any pour within the freeze window, and confirm entrained air on delivery tickets.	Sequence exterior flatwork away from the coldest 2–3 months where possible; test air content on every truck.
High	45–79.9 cycles/yr	Cold-weather curing measures (insulated blankets, heated enclosures) are standard practice, not optional, across most of the freeze season.	Exterior pours cluster in the free-season window; late fall and early spring pours need a hard-freeze contingency plan.
Severe	80+ cycles/yr	Cold-weather concreting protocols (ACI 306R) apply for a large share of the year; heated enclosures are routine.	The practical pour season is materially shorter than the calendar year; schedule exterior flatwork tightly around the free-season days figure.

Methodology

Cycle definition: An air freeze-thaw cycle is a calendar day on which the minimum temperature falls to 32 F (0 C) or below and the maximum temperature rises above 32 F (0 C).

Normal period: Each city's figures are means over the 2015–2024 period, using every year in that window with at least 350 days of complete daily temperature data at the selected station. Years with more than 15 missing days are excluded rather than gap-filled.

Station selection: For each city, SlabCalc selects the nearest NOAA NCEI Global Historical Climatology Network - Daily (GHCN-Daily) station to the city's Census Gazetteer centroid that meets the completeness threshold above for enough years in the normal period. No station used is more than 80 km from its city's centroid.

Source: NOAA NCEI Global Historical Climatology Network - Daily (GHCN-Daily) (https://www.ncei.noaa.gov/products/land-based-station/global-historical-climatology-network-daily), licensed CC BY 4.0.

Limitations

This index measures air temperature at a weather station, not concrete surface or internal temperature at a specific slab. Concrete mass, color, sun exposure, and insulation all shift the actual freeze-thaw exposure a given pour experiences relative to the station record.
A city's station can be up to 80 km from that city's centroid. In large or geographically varied metros, local microclimates — elevation, lake effect, urban heat island — can shift the true cycle count away from the station figure shown here.
Figures are means over a fixed historical period, not a forecast. Any individual year can fall meaningfully outside a city's recorded minimum-to-maximum annual cycle range, so treat the mean as a planning baseline rather than a guarantee for a specific season.

How to Cite This Dataset

This dataset is free to cite, reference, and reuse in reporting, research, or analysis under a CC BY 4.0 license — we ask only that you link back to this page as the source.

SlabCalc. (2026). “The SlabCalc Freeze-Thaw Index: Air Freeze-Thaw Cycles for 180 US Cities.” Retrieved from https://www.slabcalc.co/research/freeze-thaw-index.

Download the full dataset as CSV (180 cities). Data last updated September 17, 2026.

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