All-time weather records — San Marcos, CA

Record high
115.0°F
September 6, 2020
Record low
6.1°F
September 18, 2021
Wettest day
3.24 in
January 29, 1980

Climate change signal in San Marcos

35%

of San Marcos's all-time daily heat records were set in the last decade (128 of 366 records since 2015).

2.7%

of all-time daily cold records were set in the last decade (10 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 #
1970s
18
22
1980s
64
160
1990s
75
75
2000s
51
85
2010s
85
20
2020s
73
4

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 1979, the latest in 2026. Period of observation: 1979-2026.

Records by month

Month Hottest day Coldest day Wettest day
January 91.9°F — Jan 31, 2003 25.0°F — Jan 15, 2007 3.24 in — Jan 29, 1980
February 96.1°F — Feb 27, 2026 27.0°F — Feb 15, 1990 3.15 in — Feb 14, 2019
March 98.1°F — Mar 17, 2026 32.0°F — Mar 29, 2008 2.71 in — Mar 15, 2023
April 102.9°F — Apr 7, 1989 28.9°F — Apr 1, 2003 3.14 in — Apr 10, 2020
May 104.0°F — May 15, 2014 30.9°F — May 6, 2003 0.83 in — May 7, 2017
June 106.0°F — Jun 20, 2016 35.1°F — Jun 1, 2002 0.75 in — Jun 10, 1990
July 111.9°F — Jul 6, 2018 50.0°F — Jul 12, 1984 0.74 in — Jul 1, 1994
August 109.9°F — Aug 23, 2025 33.1°F — Aug 27, 2003 1.45 in — Aug 26, 2007
September 115.0°F — Sep 6, 2020 6.1°F — Sep 18, 2021 1.72 in — Sep 25, 1997
October 106.0°F — Oct 1, 2020 30.9°F — Oct 15, 1988 2.04 in — Oct 19, 2010
November 98.1°F — Nov 2, 1997 28.9°F — Nov 21, 1979 2.00 in — Nov 25, 1985
December 90.0°F — Dec 4, 1979 26.1°F — Dec 23, 1990 3.02 in — Dec 22, 2010

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