All-time weather records — Alton, MO

Record high
109.0°F
August 4, 2011
Record low
-18.0°F
January 11, 1977
Wettest day
8.35 in
December 3, 1982

Climate change signal in Alton

8.5%

of Alton's all-time daily heat records were set in the last decade (31 of 366 records since 2015).

2.5%

of all-time daily cold records were set in the last decade (9 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
·
·
1950s
·
·
1960s
80
81
1970s
66
118
1980s
37
51
1990s
48
38
2000s
75
57
2010s
29
12
2020s
31
9

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 1962, the latest in 2026. Period of observation: 1940-2026.

Records by month

Month Hottest day Coldest day Wettest day
January 75.9°F — Jan 24, 2002 -18.0°F — Jan 11, 1977 3.75 in — Jan 31, 1982
February 88.0°F — Feb 28, 2024 -9.9°F — Feb 7, 1982 3.71 in — Feb 13, 2007
March 91.9°F — Mar 23, 2026 1.0°F — Mar 4, 2014 6.12 in — Mar 19, 2008
April 91.9°F — Apr 23, 1980 15.1°F — Apr 8, 2007 4.75 in — Apr 5, 2025
May 95.0°F — May 27, 2012 28.0°F — May 4, 1976 4.60 in — May 12, 1950
June 102.0°F — Jun 30, 2023 39.9°F — Jun 3, 1969 3.67 in — Jun 18, 2000
July 107.1°F — Jul 31, 2012 46.0°F — Jul 5, 1972 3.35 in — Jul 19, 2002
August 109.0°F — Aug 4, 2011 45.0°F — Aug 2, 1973 4.20 in — Aug 23, 2019
September 102.9°F — Sep 4, 2000 30.9°F — Sep 29, 1967 4.77 in — Sep 23, 2006
October 96.1°F — Oct 1, 1998 16.0°F — Oct 24, 1981 3.72 in — Oct 30, 2009
November 84.9°F — Nov 9, 1980 1.0°F — Nov 29, 1976 4.77 in — Nov 17, 1958
December 75.9°F — Dec 5, 2001 -6.0°F — Dec 31, 1976 8.35 in — Dec 3, 1982

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