Every summer the same two barbecue arguments break out, “it never used to be like this” and “1936 was worse,” so we counted the 100 degree days by state, then and now, from each state’s long-record big-city weather station. Both arguments turn out to be right, in different halves of the country: Phoenix has gone from 91.8 triple-digit days a year to 112.9 while sixteen stations, mostly on the Plains and points east, actually count fewer than they used to.
Phoenix now averages 112.9 days at or above 100 degrees a year, up 21 from its 1951-1980 baseline, with a record 145 in 2020.
The Mountain West is the new record zone: Boise’s count more than doubled and Denver’s roughly quintupled from a small base.
Sixteen big-city stations count fewer 100 degree days now than then, including Wichita, Albuquerque, and New York.
Across much of the Plains the worst year on record is still 1936, when St. Louis logged 37 triple-digit days and Omaha 30.
Miami has recorded zero 100 degree days in both eras, because humidity caps thermometer highs; heat index is a different measure.
The map, your state’s then-vs-now count, and the worst year ever recorded at each station are below.
Which city has the most 100 degree days?
Phoenix, and it isn’t close: 112.9 days a year at or above 100 degrees in the current era, up from 91.8 in the 1951-1980 baseline, with an all-time record of 145 set in 2020. Las Vegas follows at 80.2, up from 74.1, and then the counts fall off a cliff to Dallas-Fort Worth’s 23.5.
The growth is a Western story. Boise jumped from 4.5 days to 10.7, Salt Lake City from 5.1 to 9.6, and Denver from 0.4 to 2.2; even Seattle, which had never recorded a triple-digit day, logged three in 2021 alone.
Map: average days per year at or above 100°F at each state’s long-record big-city station, 1995-2024 era, darkest = most (Phoenix, 112.9). One station per state; a big-city record, not a state average.Now-era triple-digit days per year, from zero (five stations) to Phoenix’s 112.9.
Source: NOAA/RCC ACIS, ThreadEx station records through 2024.
The table below shows every state’s long-record big-city station: its average 100 degree days then and now, the change, and the worst year it ever recorded. One station per state, so this is your state’s big-city thermometer, not a statewide average. Sort it however you want.
100 degree days by state: average days per year at or above 100°F at one long-record big-city station per state (NOAA ThreadEx via ACIS), two eras, plus each station’s worst year on its full record. One station per state; not a statewide average. Click a header to sort.
Rank
State
Station
Then (1951-1980)
Now (1995-2024)
Change
Worst year
Days that year
1
Arizona
Phoenix
91.8
112.9
+21.0
2020
145
2
Nevada
Las Vegas
74.1
80.2
+6.1
2024
112
3
Texas
Dallas-Fort Worth
20.4
23.5
+3.1
2011
71
4
Oklahoma
Oklahoma City
12.6
13.6
+0.9
2011
63
5
Kansas
Wichita
14.4
13.5
-0.9
2011
53
6
Idaho
Boise
4.5
10.7
+6.1
2022
27
7
Utah
Salt Lake City
5.1
9.6
+4.5
2022
34
8
Arkansas
Little Rock
7.7
8.5
+0.8
1980
47
9
South Carolina
Columbia
4.4
5.6
+1.1
1954
28
10
Mississippi
Jackson
4.5
3.9
-0.6
1902
46
11
Missouri
St Louis
2.9
3.3
+0.4
1936
37
12
New Mexico
Albuquerque
4.6
3.0
-1.6
1980
28
13
Montana
Billings
1.6
2.8
+1.2
1936
15
14
North Dakota
Bismarck
2.3
2.6
+0.4
2021
15
15
Alabama
Birmingham
1.8
2.2
+0.5
1925
15
16
Colorado
Denver
0.4
2.2
+1.8
2012
13
17
Nebraska
Omaha
2.9
2.0
-0.9
1936
30
18
Oregon
Portland
0.8
1.6
+0.8
1941
5
19
Maryland
Baltimore
0.7
1.4
+0.7
2024
8
20
District of Columbia
Washington
0.7
1.3
+0.6
1930
11
21
New Jersey
Newark
0.9
1.3
+0.5
1993
9
22
Tennessee
Nashville
2.1
1.3
-0.8
1954
20
23
Kentucky
Louisville
1.0
1.0
-0.0
1936
16
24
Louisiana
New Orleans
0.2
0.9
+0.7
2023
17
25
North Carolina
Charlotte
1.1
0.9
-0.2
1954
10
26
Iowa
Des Moines
1.2
0.8
-0.4
1936
27
27
South Dakota
Sioux Falls
1.8
0.8
-1.1
1936
21
28
Virginia
Norfolk
0.5
0.8
+0.3
1942
5
29
Georgia
Atlanta
0.7
0.7
+0.0
1980
9
30
Indiana
Indianapolis
0.3
0.4
+0.1
1936
12
31
California
Los Angeles Airport
1.1
0.3
-0.8
1963
4
32
Connecticut
Hartford
0.3
0.3
-0.0
1991
3
33
Illinois
Chicago
0.5
0.3
-0.2
1988
7
34
New York
New York-Central Park
0.7
0.3
-0.4
1953
4
35
Pennsylvania
Philadelphia
0.6
0.3
-0.2
1988
5
36
Delaware
Wilmington
0.5
0.2
-0.3
1896
6
37
Massachusetts
Boston
0.2
0.2
+0.0
1911
4
38
Michigan
Detroit
0.2
0.2
-0.1
1936
8
39
Minnesota
Minneapolis-St Paul
0.2
0.2
+0.0
1936
9
40
Ohio
Columbus
0.2
0.2
-0.1
1936
9
41
Rhode Island
Providence
0.1
0.2
+0.1
1944
3
42
West Virginia
Charleston
0.2
0.2
+0.0
1931
22
43
Wisconsin
Milwaukee
0.1
0.2
+0.2
1988
6
44
New Hampshire
Concord
0.2
0.1
-0.1
1911
4
45
Vermont
Burlington
0.0
0.1
+0.1
1995
2
46
Washington
Seattle Tacoma
0.0
0.1
+0.1
2021
3
47
Alaska
Anchorage
0.0
0.0
+0.0
1953
0
48
Florida
Miami
0.0
0.0
+0.0
1942
1
49
Hawaii
Honolulu
0.0
0.0
+0.0
1940
0
50
Maine
Portland
0.0
0.0
+0.0
1948
2
51
Wyoming
Cheyenne
0.0
0.0
-0.0
1881
2
Source: NOAA/RCC ACIS ThreadEx station records through 2024.
Where are 100 degree days actually declining?
Sixteen of the 51 stations, and they cluster in the middle and east of the country. Wichita slipped from 14.4 days to 13.5, Jackson from 4.5 to 3.9, Albuquerque from 4.6 to 3.0, Omaha from 2.9 to 2.0, and New York’s Central Park from 0.7 to 0.3.
The reason lives in the record books. Across the Plains, the worst triple-digit year ever measured is still 1936, the Dust Bowl summer, when St. Louis hit 100 on 37 days, Omaha on 30, Des Moines on 27, and Sioux Falls on 21.
Out west it’s the opposite. Phoenix set its record in 2020 and Dallas-Fort Worth in 2011, with 71.
Change in average 100°F days per year, then-era vs now-era: the six biggest risers and five biggest declines.
Phoenix+21.0
Las Vegas+6.1
Boise+6.1
Salt Lake City+4.5
Dallas-Fort Worth+3.1
Denver+1.8
Albuquerque-1.6
Sioux Falls-1.1
Wichita-0.9
Omaha-0.9
Nashville-0.8
Source: NOAA/RCC ACIS ThreadEx records; eras 1951-1980 vs 1995-2024.
So was 1936 worse, or is now worse?
Both, depending on where you’re standing, which is why the argument never resolves. If you’re in St. Louis, Omaha, or Des Moines, your city’s most brutal 100 degree summer really did happen ninety years ago, and today’s counts sit near or below the old baseline.
If you’re in Phoenix, Boise, Salt Lake City, or Dallas, the records are being set now.
The 100 degree belt hasn’t just intensified. It has moved west.
Two eras, three exhibits.
Phoenix91.8 → 112.9 days a year, record 145 in 2020the new-record West
Boise4.5 → 10.7 days a year, more than doubledthe fastest-changing tier
St. Louisworst year still 1936, with 37 triple-digit daysthe Dust Bowl’s standing record
Source: NOAA/RCC ACIS ThreadEx records.
Methodology: where these numbers come from
Counts come from NOAA’s ThreadEx long-record station threads, one per state, chosen as the state’s largest or most iconic city with a continuous record, and computed server-side by the Regional Climate Centers’ ACIS system: days per year with a maximum temperature at or above 100 degrees Fahrenheit. The two eras are 1951-1980, the classic climate-normals baseline, and 1995-2024; the worst-year column searches each station’s full record, which reaches the 1870s-1890s at many stations. Missing years are excluded from era averages.
Three honest limits. One station per state means big-city records, not statewide averages, and never a national roll-up. Los Angeles’ station is coastal LAX; inland California runs far hotter.
And the threshold is the thermometer’s 100, not the heat index, so humid places like Miami can be dangerously hot without ever appearing in this table. Heat is also the dominant hazard in seven states’ riskiest counties, per our riskiest county in every state page.
Stations: NOAA ThreadEx threaded city records, one per state, meta-verified
Counts: ACIS server-side yearly count of days with max temp ≥100°F
Eras: 1951-1980 vs 1995-2024; worst year from the full record
Thermometer highs only; heat index excluded by design
The bottom line
The 100 degree map of America is two stories: a West setting records year after year, and a middle where the Dust Bowl summer of 1936 still stands as the worst. Your state’s row above says which story you live in.
Next time the argument breaks out at the barbecue, bring the table. Everyone gets to be right somewhere.
Frequently asked questions
How many 100 degree days does Florida get?
Miami has recorded zero days at or above 100 degrees in both the 1951-1980 and 1995-2024 eras, per its long-record station. Coastal humidity keeps thermometer highs just short of the mark while making the heat index far worse. Florida heat is dangerous through humidity, not triple-digit readings.
How many days over 100 degrees does Portland, Oregon get?
Portland’s long-record station averages 1.6 days at or above 100 degrees in the current era, double its 0.8 baseline; its record year is 1941 with 5, though the station’s record only begins in 1940. The Pacific Northwest’s new triple-digit era is clearer in Seattle, which logged its first-ever 100 degree days in 2021, three of them.
Was 1936 hotter than today?
In much of the middle of the country, yes: 1936 remains the worst 100 degree year ever recorded in St. Louis with 37 days, Omaha with 30, Des Moines with 27, and Sioux Falls with 21. In the West it’s no contest the other way: Phoenix’s record 145 came in 2020 and Dallas-Fort Worth’s 71 in 2011. Where you stand decides which era wins.
Which cities never hit 100 degrees?
Among the 51 big-city stations here, Anchorage, Honolulu, Portland (Maine), Miami, and Cheyenne have averaged zero 100 degree days in both eras. Honolulu and Miami are capped by ocean humidity, Anchorage by latitude, and Cheyenne by its 6,000-foot elevation. Zero on the thermometer doesn’t mean comfortable.
Sources
NOAA Regional Climate Centers. “Applied Climate Information System (ACIS): ThreadEx Long-Record Station Data (daily maximum temperature, yearly counts at or above 100°F).” 2026. www.rcc-acis.org/
NOAA National Weather Service / ThreadEx. “Threaded Station Extremes (station documentation).” 2026. threadex.rcc-acis.org/
Chris Kolmar has been in the real estate business for almost ten years now. He originally worked for Movoto Real Estate as the director of marketing before founding HomeSnacks.
He believes the key to finding the right place to live comes down to looking at the data, reading about things to do, and, most importantly, checking it out yourself before you move.
If you've been looking for a place to live in the past several years, you've probably stumbled upon his writing already.
