Weather on December 18
San Marcos, CA
55 Years of Data
Avg High
69°F
Avg Low
44°F
Warmest
1997
70°F avg
Coldest
1984
48°F avg
About This Date
December 18th in San Marcos, CA typically brings mild winter weather, with average highs around 69°F and lows near 44°F — a 25°F daily swing. Over 55 years of records, the warmest December 18th was in 1997 (70°F average), while the coldest was 1984 (48°F) — a 22°F range across recorded history. Rain or other precipitation has occurred on about 25% of December 18th dates historically, with the wettest December 18th recording 3.3" of rain. Temperatures on this date have remained relatively stable over the past several decades.
Temperatures on this date have remained relatively stable over the past several decades.
Planning for December 18th in San Marcos, CA? Great weather for outdoor activities.
Warming Trend
0.5°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 85° | 48° | 66° | — | — |
| 2024 | 86° | 46° | 66° | — | — |
| 2023 | 79° | 50° | 64° | — | — |
| 2022 | 68° | 42° | 55° | — | — |
| 2021 | 70° | 37° | 53° | — | — |
| 2020 | 70° | 45° | 57° | — | — |
| 2019 | 65° | 38° | 51° | — | — |
| 2018 | 67° | 49° | 58° | — | — |
| 2017 | 72° | 41° | 56° | — | — |
| 2016 | 65° | 34° | 49° | — | — |
| 2015 | 72° | 38° | 55° | — | — |
| 2014 | 64° | 51° | 58° | 0.03" | — |
| 2013 | 72° | 54° | 63° | — | — |
| 2012 | 58° | 54° | 56° | 0.36" | — |
| 2011 | 58° | 47° | 52° | — | — |
| 2010 | 61° | 56° | 58° | 1.3" | — |
| 2009 | 73° | 49° | 61° | — | — |
| 2008 | 56° | 44° | 50° | 0.03" | — |
| 2007 | 61° | 46° | 53° | 0.43" | — |
| 2006 | 60° | 35° | 48° | — | — |
| 2005 | 62° | 45° | 53° | — | — |
| 2004 | 80° | — | — | — | — |
| 2003 | 79° | 41° | 60° | — | — |
| 2002 | 59° | 39° | 49° | 0.1" | — |
| 2001 | 69° | 35° | 52° | — | — |
| 2000 | 78° | 44° | 61° | — | — |
| 1999 | 72° | 49° | 60° | — | — |
| 1998 | 60° | 54° | 57° | — | — |
| 1997warmest | 78° | 62° | 70° | 0.18" | — |
| 1996 | 69° | 50° | 60° | — | — |
| 1995 | 68° | 36° | 52° | — | — |
| 1994 | 71° | 36° | 53° | — | — |
| 1993 | 64° | 36° | 50° | — | — |
| 1992 | 58° | 47° | 52° | 1.02" | — |
| 1991 | 61° | 53° | 57° | 0.66" | — |
| 1990 | 65° | 36° | 50° | — | — |
| 1989 | 65° | 39° | 52° | — | — |
| 1988 | 61° | 42° | 51° | 0.43" | — |
| 1987 | 67° | 40° | 53° | 0.15" | — |
| 1986 | 68° | 52° | 60° | — | — |
| 1985 | 81° | 43° | 62° | — | — |
| 1984coldest | 55° | 41° | 48° | 1.3" | — |
| 1983 | 68° | 40° | 54° | — | — |
| 1982 | 72° | 34° | 53° | — | — |
| 1981 | 73° | 41° | 57° | — | — |
| 1980 | 72° | 43° | 57° | — | — |
| 1979 | 82° | 40° | 61° | — | — |
| 1978 | 58° | 48° | 53° | 3.3" | — |
| 1977 | 64° | 54° | 59° | 1.57" | — |
| 1976 | 69° | 40° | 54° | — | — |
| 1975 | 72° | 31° | 51° | — | — |
| 1974 | 76° | 35° | 55° | — | — |
| 1973 | 70° | 47° | 58° | — | — |
| 1972 | 78° | 42° | 60° | — | — |
| 1971 | 67° | 38° | 52° | — | — |
55 years of data from ESCONDIDO #2