Basilemorin / CC0
San Marcos, CA Weather on April 20
April 20th in San Marcos, CA typically brings pleasant spring weather, with average highs around 75°F and lows near 50°F — a 25°F daily swing. Over 55 years of records, the warmest April 20th was in 2009 (79°F average), while the coldest was 1982 (48°F) — a 31°F range across recorded history. Rain or other precipitation has occurred on about 11% of April 20th dates historically, with the wettest April 20th recording 3.18" of rain. The last decade has been 1.2°F warmer on this date compared to 20-30 years ago.
What to Expect on April 20
Planning for April 20th in San Marcos, CA? Great weather for outdoor activities.
April 20 Weather Records for San Marcos
- •The all-time record high for April 20th in San Marcos, CA is 96°F, set in 2009.
- •The coldest April 20th on record dropped to 37°F in 1972.
- •Temperatures have reached 90°F or higher on April 20th in 3 of the last 55 years.
- •Last year (1971), April 20th was 16°F cooler than the long-term average.
Frequently Asked Questions
What was the warmest April 20 ever in San Marcos?
The warmest April 20 in San Marcos, CA reached 96°F in 2009. That is 21°F above the long-term average high of 75°F.
What was the coldest April 20 ever in San Marcos?
The coldest April 20 in San Marcos, CA dropped to 37°F in 1972. That is 13°F below the long-term average low of 50°F.
What is the average temperature on April 20 in San Marcos?
On April 20, San Marcos averages a high of 75°F and a low of 50°F based on 55 years of NOAA weather observations from ESCONDIDO #2.
How many years of weather data are available for April 20 in San Marcos?
We have 55 years of weather records for April 20 in San Marcos, CA, sourced from NOAA's Global Historical Climatology Network. Records include daily high and low temperatures, precipitation, and snowfall data going back to 2025.
April 20 Weather History in San Marcos
| Year | High | Low | Precip | Snow |
|---|---|---|---|---|
| 2025 | 77°F | 49°F | 0" | -- |
| 2024 | 78°F | 56°F | 0" | -- |
| 2023 | 82°F | 49°F | 0" | -- |
| 2022 | 74°F | 56°F | 0" | -- |
| 2021 | 77°F | 53°F | 0" | -- |
| 2020 | 69°F | 56°F | 0" | -- |
| 2019 | 70°F | 55°F | 0" | -- |
| 2018 | 77°F | 47°F | 0" | -- |
| 2017 | 79°F | 53°F | 0" | -- |
| 2016 | 89°F | 53°F | 0" | -- |
| 2015 | 73°F | 58°F | 0" | -- |
| 2014 | 78°F | 54°F | 0" | -- |
| 2013 | 84°F | 48°F | 0" | -- |
| 2012 | 82°F | 53°F | 0" | -- |
| 2011 | 68°F | 57°F | 0" | -- |
| 2010 | 65°F | 54°F | 0.05" | -- |
| 2009 | 96°F | 62°F | 0" | -- |
| 2008 | 61°F | 50°F | 0" | -- |
| 2007 | 59°F | 48°F | 1.14" | -- |
| 2006 | 71°F | 54°F | 0" | -- |
| 2005 | 81°F | 46°F | 0" | -- |
| 2004 | 73°F | 48°F | 0" | -- |
| 2003 | 78°F | 46°F | 0" | -- |
| 2002 | 71°F | 46°F | 0" | -- |
| 2001 | 71°F | 48°F | 0" | -- |
| 2000 | 80°F | 48°F | 0" | -- |
| 1999 | 91°F | 53°F | 0" | -- |
| 1998 | 83°F | 51°F | 0" | -- |
| 1997 | 81°F | 60°F | 0" | -- |
| 1996 | 71°F | 45°F | 0" | -- |
| 1995 | 62°F | 44°F | 0" | -- |
| 1994 | 78°F | 55°F | 0" | -- |
| 1993 | 90°F | 53°F | 0" | -- |
| 1992 | 88°F | 52°F | 0" | -- |
| 1991 | 72°F | 53°F | 0" | -- |
| 1990 | 64°F | 57°F | 0" | -- |
| 1989 | 82°F | 55°F | 0" | -- |
| 1988 | 69°F | 51°F | 3.18" | -- |
| 1987 | 86°F | 48°F | 0" | -- |
| 1986 | 89°F | 51°F | 0" | -- |
| 1985 | 66°F | 53°F | 0" | -- |
| 1984 | 69°F | 45°F | 0" | -- |
| 1983 | 69°F | 52°F | 0.58" | -- |
| 1982 | 47°F | 49°F | 0" | -- |
| 1981 | 68°F | 46°F | 0" | -- |
| 1980 | 82°F | 54°F | 0" | -- |
| 1979 | 72°F | 44°F | 0" | -- |
| 1978 | 71°F | 52°F | 0" | -- |
| 1977 | 74°F | 43°F | 0" | -- |
| 1976 | 83°F | 47°F | 0" | -- |
| 1975 | 74°F | 42°F | 0" | -- |
| 1974 | 68°F | 43°F | 0" | -- |
| 1973 | 65°F | 43°F | 0.2" | -- |
| 1972 | 70°F | 37°F | 0.08" | -- |
| 1971 | 59°F | 48°F | 0" | -- |
Based on 55 years of data from NOAA station: ESCONDIDO #2
Monthly Climate Averages
Historical temperature and precipitation averages for San Marcos, CA, based on 55+ years of weather data.
Temperatures in Fahrenheit. Precipitation and snowfall in inches.