April is one of the cooler months of the year in San Mateo, with average highs near 14.7°C and lows around 9.7°C (mean 12.2°C). It is one of the drier months, averaging 32 mm of rainfall and 83% relative humidity across the period.
April is one of the cooler months of the year in San Mateo. Across 45 years of records, the warmest April in San Mateo was 1992 — when the month averaged 14.3°C — while the coldest was 2001 at 10.6°C. Typical April days reach 14.7°C with nights near 9.7°C. The long-term April temperature trend is broadly flat.
April is one of the drier months in San Mateo, averaging 32 mm of rainfall. The wettest April on record was 2006 with 123 mm, while the driest were 2008 and 2021 at 3 mm.
Relative humidity in San Mateo during April averages 83%. The most humid April was 2019 at 87%, and the least humid were 1983 and 2008 at 80%.
April receives about 6 kWh/m²/day of solar energy in San Mateo. The sunniest April was 2022 at 6.8 kWh/m²/day, and the cloudiest was 2006 at 4.7.
Average wind speed in San Mateo during April is 4 m/s. The windiest Aprils were 1984 and 1999 at 4.7 m/s, while the calmest was 1989 at 2.8 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.3°C | 12.4°C | 11.7°C | 12.5°C | 12.0°C | -0.3°C |
| Avg High | 15.0°C | 15.0°C | 14.0°C | 15.0°C | 14.4°C | -0.6°C |
| Avg Low | 9.6°C | 9.8°C | 9.3°C | 10.1°C | 9.6°C | 0°C |
| Avg Rain | 31 mm | 26 mm | 39 mm | 38 mm | 21 mm | -9 mm |
April temperatures in San Mateo have stayed relatively stable across the record.
April has ranged from a record low of 5.1°C (1999) to a record high of 26.5°C (2014).
Rainfall in April is one of the drier months, averaging 32 mm, with a wettest year of 123 mm.
Daytime highs and overnight lows have shifted differently — highs fell about 0.1°C per decade while lows rose 0.1°C per decade, narrowing the gap between day and night.
A good time to visit San Mateo
April is a good time to visit San Mateo, with days averaging 14.7°C and nights around 9.7°C (mean 12.2°C, cooler than San Mateo's yearly average) and moderate rainfall. September and August are marginally more temperate, but April still suits most travellers.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 14.5°C | 12.3°C | 10.2°C | 19.4°C | 8.8°C | 11 mm | 86% | 3.3 m/s | 5.6 |
| 2024 | 14.8°C | 12.5°C | 10.1°C | 18.9°C | 6.9°C | 37 mm | 85% | 4.1 m/s | 6.2 |
| 2023 | 13.4°C | 11.0°C | 8.7°C | 17.3°C | 6.3°C | 5 mm | 85% | 4.1 m/s | 6.6 |
| 2022 | 14.8°C | 12.1°C | 9.4°C | 25.0°C | 7.3°C | 32 mm | 82% | 4.6 m/s | 6.8 |
| 2021 | 13.6°C | 11.3°C | 9.0°C | 21.1°C | 8.1°C | 3 mm | 85% | 4.1 m/s | 6.2 |
| 2020 | 15.0°C | 12.8°C | 10.5°C | 19.9°C | 8.2°C | 39 mm | 83% | 4.1 m/s | 5.7 |
| 2019 | 15.7°C | 13.3°C | 11.0°C | 22.6°C | 9.5°C | 12 mm | 87% | 3.5 m/s | 5.7 |
| 2018 | 14.9°C | 12.4°C | 10.0°C | 20.5°C | 8.0°C | 55 mm | 83% | 3.8 m/s | 6 |
| 2017 | 15.3°C | 13.0°C | 10.7°C | 18.9°C | 8.4°C | 63 mm | 84% | 3.9 m/s | 5.8 |
| 2016 | 16.3°C | 13.8°C | 11.3°C | 25.7°C | 8.5°C | 38 mm | 83% | 3.7 m/s | 6.1 |
| 2015 | 15.2°C | 12.6°C | 10.1°C | 24.3°C | 8.8°C | 29 mm | 81% | 3.9 m/s | 6.4 |
| 2014 | 15.8°C | 13.2°C | 10.5°C | 26.5°C | 8.5°C | 26 mm | 83% | 3.5 m/s | 6.1 |
| 2013 | 15.3°C | 12.4°C | 9.5°C | 21.6°C | 6.8°C | 14 mm | 82% | 3.9 m/s | 6.5 |
| 2012 | 14.3°C | 12.0°C | 9.7°C | 21.3°C | 6.4°C | 49 mm | 85% | 4 m/s | 6 |
| 2011 | 13.3°C | 11.2°C | 9.0°C | 19.5°C | 6.1°C | 10 mm | 84% | 4.4 m/s | 6.1 |
| 2010 | 13.7°C | 11.4°C | 9.2°C | 17.8°C | 7.8°C | 82 mm | 82% | 4.4 m/s | 5.8 |
| 2009 | 14.1°C | 11.4°C | 8.7°C | 25.8°C | 6.5°C | 14 mm | 81% | 4.3 m/s | 6.4 |
| 2008 | 13.9°C | 11.1°C | 8.3°C | 23.4°C | 5.9°C | 3 mm | 80% | 4.2 m/s | 6.7 |
| 2007 | 14.0°C | 11.5°C | 9.0°C | 20.0°C | 7.0°C | 28 mm | 85% | 4.2 m/s | 6.2 |
| 2006 🌧️ | 13.8°C | 12.1°C | 10.3°C | 18.6°C | 8.3°C | 123 mm | 87% | 3.8 m/s | 4.7 |
| 2005 | 14.3°C | 12.0°C | 9.6°C | 18.2°C | 7.0°C | 42 mm | 84% | 4.1 m/s | 6.3 |
| 2004 | 15.5°C | 12.7°C | 9.9°C | 26.0°C | 7.7°C | 5 mm | 83% | 3.4 m/s | 6.2 |
| 2003 | 13.2°C | 11.3°C | 9.5°C | 16.1°C | 6.9°C | 86 mm | 82% | 4.2 m/s | 5.6 |
| 2002 | 13.8°C | 11.8°C | 9.7°C | 19.5°C | 7.4°C | 11 mm | 85% | 3.8 m/s | 5.4 |
| 2001 ❄️ | 12.9°C | 10.6°C | 8.3°C | 20.1°C | 6.3°C | 37 mm | 84% | 4.3 m/s | 6.1 |
| 2000 | 14.6°C | 12.3°C | 10.0°C | 21.0°C | 8.4°C | 35 mm | 85% | 3.9 m/s | 5.9 |
| 1999 | 13.6°C | 10.8°C | 8.1°C | 23.2°C | 5.1°C | 40 mm | 82% | 4.7 m/s | 6.1 |
| 1998 | 14.0°C | 11.8°C | 9.6°C | 23.1°C | 7.7°C | 37 mm | 83% | 4.1 m/s | 5.9 |
| 1997 | 15.2°C | 12.4°C | 9.5°C | 19.5°C | 7.2°C | 11 mm | 84% | 4.4 m/s | 6.2 |
| 1996 | 16.1°C | 13.3°C | 10.6°C | 22.3°C | 8.7°C | 35 mm | 84% | 3.6 m/s | 6.2 |
| 1995 | 14.2°C | 11.8°C | 9.5°C | 19.4°C | 6.6°C | 50 mm | 86% | 4.5 m/s | 5.8 |
| 1994 | 15.0°C | 12.5°C | 9.9°C | 19.2°C | 8.2°C | 35 mm | 84% | 4 m/s | 5.8 |
| 1993 | 15.0°C | 12.6°C | 10.2°C | 17.8°C | 8.4°C | 19 mm | 85% | 4 m/s | 6.4 |
| 1992 🔥 | 17.0°C | 14.3°C | 11.6°C | 22.1°C | 8.9°C | 14 mm | 84% | 4 m/s | 6 |
| 1991 | 14.0°C | 11.4°C | 8.8°C | 19.0°C | 6.9°C | 12 mm | 83% | 4.4 m/s | 6.3 |
| 1990 | 15.8°C | 13.2°C | 10.5°C | 22.0°C | 7.0°C | 10 mm | 83% | 4 m/s | 5.7 |
| 1989 | 16.4°C | 13.6°C | 10.7°C | 23.2°C | 8.4°C | 17 mm | 82% | 2.8 m/s | 5.8 |
| 1988 | 15.0°C | 12.4°C | 9.7°C | 23.2°C | 7.0°C | 39 mm | 80% | 3.6 m/s | 5.6 |
| 1987 | 16.1°C | 13.0°C | 10.0°C | 22.2°C | 8.1°C | 9 mm | 81% | 3.7 m/s | 6.1 |
| 1986 | 14.5°C | 12.0°C | 9.5°C | 21.3°C | 7.3°C | 17 mm | 82% | 4.2 m/s | 6 |
| 1985 | 15.4°C | 12.4°C | 9.5°C | 22.5°C | 8.4°C | 7 mm | 84% | 3.6 m/s | 5.7 |
| 1984 | 13.9°C | 11.3°C | 8.6°C | 22.8°C | 6.7°C | 20 mm | 81% | 4.7 m/s | 6.3 |
| 1983 | 14.0°C | 11.9°C | 9.8°C | 17.0°C | 6.3°C | 86 mm | 80% | 4.5 m/s | — |
| 1982 | 14.2°C | 11.8°C | 9.4°C | 21.3°C | 5.8°C | 68 mm | 81% | 4.3 m/s | — |
| 1981 | 15.3°C | 12.3°C | 9.3°C | 25.8°C | 7.4°C | 14 mm | 82% | 4.1 m/s | — |
Actual recorded April data for each year, 1981–2025 — sourced from NASA POWER.
The average high in April is around 14.7°C with lows near 9.7°C (mean 12.2°C), based on 45 years of NASA POWER data.
April averages 32 mm of rainfall in San Mateo, one of the drier months. The wettest on record was 123 mm in 2006.
The hottest April reached 26.5°C in 2014. The coldest dipped to 5.1°C in 1999.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average April temperatures have fallen by about 0.1°C — but days and nights have moved in opposite directions. Overnight lows rose from 9.3°C to 9.5°C while daytime highs eased from 14.6°C to 14.2°C, narrowing the gap between day and night.
April is one of the cooler months of the year in San Mateo and one of the drier months, so plan for around 14.7°C daytime highs and 9.7°C at night.
Not quite — April is the 5th coolest month in San Mateo, averaging 12.2°C.
For April in San Mateo, pack light layers you can adjust through the day, with typical highs of 14.7°C and lows of 9.7°C.
Relative humidity in April averages 83% — quite humid.
Average wind speed in April is 4 m/s. The windiest April on record averaged 4.7 m/s (1984).
The wettest April on record was 2006 with 123 mm. On average, April sees 32 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in San Mateo behaves each April, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for April specifically, along with year-by-year records and how the month has changed over the decades.
