All-time weather records — Boulder, MT

Record high
100.9°F
July 14, 2002
Record low
-42.0°F
December 22, 1990
Wettest day
1.85 in
July 10, 1983

Climate change signal in Boulder

13.9%

of Boulder's all-time daily heat records were set in the last decade (51 of 366 records since 2015).

6.6%

of all-time daily cold records were set in the last decade (24 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 #
1940s
8
9
1950s
48
61
1960s
52
63
1970s
33
52
1980s
66
51
1990s
47
59
2000s
45
41
2010s
32
9
2020s
35
21

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 1948, the latest in 2026. Period of observation: 1880-2026.

Records by month

Month Hottest day Coldest day Wettest day
January 59.0°F — Jan 18, 2026 -38.0°F — Jan 26, 1957 1.40 in — Jan 6, 2022
February 64.9°F — Feb 20, 1995 -38.9°F — Feb 3, 1989 0.60 in — Feb 17, 1986
March 73.9°F — Mar 22, 2026 -27.9°F — Mar 25, 1955 0.52 in — Mar 16, 1965
April 82.9°F — Apr 28, 1987 -15.0°F — Apr 1, 1994 1.37 in — Apr 26, 1955
May 89.1°F — May 19, 1954 0.0°F — May 13, 1995 1.70 in — May 24, 1981
June 96.1°F — Jun 15, 2021 21.9°F — Jun 1, 1954 1.53 in — Jun 10, 2006
July 100.9°F — Jul 14, 2002 28.9°F — Jul 20, 1993 1.85 in — Jul 10, 1983
August 100.0°F — Aug 5, 1961 19.0°F — Aug 25, 1992 1.55 in — Aug 7, 2023
September 96.1°F — Sep 6, 2022 8.1°F — Sep 17, 1965 1.18 in — Sep 8, 1995
October 89.1°F — Oct 5, 1988 -14.1°F — Oct 30, 1991 1.20 in — Oct 18, 2020
November 71.1°F — Nov 2, 2025 -34.1°F — Nov 16, 1959 1.05 in — Nov 29, 1971
December 64.9°F — Dec 1, 2021 -42.0°F — Dec 22, 1990 0.62 in — Dec 3, 1948

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