All-time weather records — Boulder, CO

Record high
104.0°F
June 23, 1954
Record low
-33.0°F
January 17, 1930
Wettest day
9.08 in
September 12, 2013

Climate change signal in Boulder

19.4%

of Boulder's all-time daily heat records were set in the last decade (71 of 366 records since 2015).

7.9%

of all-time daily cold records were set in the last decade (29 of 366 records since 2015).

If records were spread evenly across the station's history, you'd expect roughly 5% per decade. Decade-by-decade, here's where each record-breaking day was set:

Decade Heat records set # Cold records set #
1890s
2
17
1900s
16
36
1910s
12
40
1920s
15
33
1930s
23
56
1940s
24
17
1950s
44
16
1960s
20
24
1970s
12
26
1980s
43
17
1990s
25
27
2000s
42
18
2010s
39
19
2020s
49
20

Records are the all-time daily extremes that are still standing — each daily record can only be held by one year. The station's earliest hot record was set in 1895, the latest in 2026. Period of observation: 1893-2026.

Records by month

Month Hottest day Coldest day Wettest day
January 73.9°F — Jan 22, 1925 -33.0°F — Jan 17, 1930 1.04 in — Jan 6, 1998
February 79.0°F — Feb 8, 1954 -27.9°F — Feb 8, 1936 1.58 in — Feb 3, 2024
March 89.1°F — Mar 21, 2026 -13.0°F — Mar 9, 1932 2.67 in — Mar 24, 1909
April 88.0°F — Apr 21, 1989 -2.9°F — Apr 2, 1975 3.56 in — Apr 3, 1986
May 95.0°F — May 28, 2000 17.1°F — May 2, 2013 3.51 in — May 17, 1995
June 104.0°F — Jun 23, 1954 14.0°F — Jun 17, 1935 3.40 in — Jun 4, 1949
July 104.0°F — Jul 11, 1954 39.9°F — Jul 4, 1903 4.80 in — Jul 31, 1919
August 102.0°F — Aug 24, 1936 39.9°F — Aug 10, 1912 3.06 in — Aug 3, 1951
September 100.0°F — Sep 2, 1983 15.1°F — Sep 30, 1985 9.08 in — Sep 12, 2013
October 91.9°F — Oct 25, 1901 -2.0°F — Oct 29, 1917 2.50 in — Oct 15, 1916
November 81.0°F — Nov 2, 2025 -11.9°F — Nov 27, 1919 1.33 in — Nov 26, 2019
December 75.9°F — Dec 17, 1980 -24.0°F — Dec 22, 1990 1.47 in — Dec 5, 1913

Click a month to see every daily record for that month in Boulder.