October is one of the warmer months of the year in San Mateo, with average highs near 18.7°C and lows around 12.7°C (mean 15.7°C). It is one of the drier months, averaging 28 mm of rainfall and 80% relative humidity across the period.
October is one of the warmer months of the year in San Mateo. Across 45 years of records, the warmest Octobers in San Mateo were 2014 and 2015 — when the month averaged 18°C — while the coldest was 2000 at 14.1°C. Typical October days reach 18.7°C with nights near 12.7°C. The long-term trend is warming, about 0.3°C per decade.
October is one of the drier months in San Mateo, averaging 28 mm of rainfall. The wettest October on record was 2021 with 141 mm, while the driest was 2020 at 0 mm.
Relative humidity in San Mateo during October averages 80%. The most humid October was 2000 at 86%, and the least humid was 2019 at 68%.
October receives about 3.9 kWh/m²/day of solar energy in San Mateo. The sunniest October was 2019 at 4.6 kWh/m²/day, and the cloudiest was 1988 at 2.9.
Average wind speed in San Mateo during October is 3 m/s. The windiest Octobers were 1984 and 2009 at 3.7 m/s, while the calmest was 1987 at 2.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 15.4°C | 15.6°C | 15.0°C | 16.3°C | 16.5°C | +1.1°C |
| Avg High | 18.4°C | 18.8°C | 17.9°C | 19.2°C | 19.4°C | +1°C |
| Avg Low | 12.3°C | 12.5°C | 12.1°C | 13.3°C | 13.5°C | +1.2°C |
| Avg Rain | 30 mm | 18 mm | 33 mm | 26 mm | 33 mm | +3 mm |
October temperatures in San Mateo have risen by about 1°C between 1981–1985 and 2021–2025.
October has ranged from a record low of 7.6°C (1989) to a record high of 31.4°C (1987).
Rainfall in October is one of the drier months, averaging 28 mm, with a wettest year of 141 mm.
One of the best times to visit San Mateo
October is one of the best times to visit San Mateo. Expect days averaging 18.7°C and nights around 12.7°C (mean 15.7°C) — warmer than San Mateo's yearly average — with low rainfall (28 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 19.1°C | 16.5°C | 13.9°C | 25.1°C | 11.3°C | 43 mm | 84% | 3 m/s | 3.7 |
| 2024 | 20.0°C | 16.9°C | 13.8°C | 31.0°C | 10.9°C | 4 mm | 79% | 2.9 m/s | 4.4 |
| 2023 | 20.5°C | 17.2°C | 13.9°C | 29.0°C | 10.4°C | 9 mm | 79% | 2.7 m/s | 4.1 |
| 2022 | 17.6°C | 15.2°C | 12.8°C | 26.5°C | 10.7°C | 1 mm | 85% | 2.8 m/s | 3.6 |
| 2021 🌧️ | 18.0°C | 15.4°C | 12.9°C | 25.4°C | 10.7°C | 141 mm | 81% | 3.6 m/s | 3.9 |
| 2020 | 21.2°C | 17.5°C | 13.8°C | 28.7°C | 11.7°C | 0 mm | 76% | 2.4 m/s | 4 |
| 2019 | 20.0°C | 16.3°C | 12.5°C | 28.3°C | 8.1°C | 1 mm | 68% | 2.9 m/s | 4.6 |
| 2018 | 19.6°C | 16.6°C | 13.6°C | 23.7°C | 12.0°C | 6 mm | 80% | 2.7 m/s | 4.1 |
| 2017 | 20.4°C | 16.5°C | 12.6°C | 28.2°C | 10.9°C | 7 mm | 71% | 2.8 m/s | 4.4 |
| 2016 | 18.2°C | 15.9°C | 13.6°C | 26.4°C | 12.2°C | 102 mm | 84% | 3.4 m/s | 3.6 |
| 2015 | 20.8°C | 18.0°C | 15.3°C | 26.7°C | 13.1°C | 7 mm | 84% | 2.5 m/s | 4.1 |
| 2014 🔥 | 20.9°C | 18.0°C | 15.1°C | 29.0°C | 13.0°C | 16 mm | 79% | 2.7 m/s | 4 |
| 2013 | 17.4°C | 14.5°C | 11.5°C | 24.4°C | 10.1°C | 14 mm | 75% | 2.6 m/s | 4.2 |
| 2012 | 18.3°C | 15.7°C | 13.2°C | 28.2°C | 11.2°C | 25 mm | 82% | 2.8 m/s | 3.9 |
| 2011 | 18.9°C | 16.0°C | 13.1°C | 25.3°C | 11.1°C | 38 mm | 83% | 2.5 m/s | 3.8 |
| 2010 | 17.6°C | 15.1°C | 12.6°C | 27.4°C | 9.2°C | 45 mm | 82% | 3 m/s | 3.5 |
| 2009 | 17.1°C | 14.5°C | 12.0°C | 20.9°C | 9.6°C | 90 mm | 84% | 3.7 m/s | 3.9 |
| 2008 | 19.5°C | 15.9°C | 12.4°C | 26.8°C | 10.3°C | 21 mm | 75% | 3.1 m/s | 4.1 |
| 2007 | 17.5°C | 14.6°C | 11.7°C | 26.3°C | 10.1°C | 40 mm | 82% | 3.1 m/s | 3.9 |
| 2006 | 18.6°C | 15.6°C | 12.6°C | 25.4°C | 10.4°C | 9 mm | 75% | 2.7 m/s | 3.7 |
| 2005 | 17.6°C | 14.6°C | 11.7°C | 24.1°C | 10.2°C | 10 mm | 84% | 3 m/s | 4 |
| 2004 | 17.6°C | 14.9°C | 12.2°C | 27.5°C | 9.8°C | 75 mm | 80% | 3.2 m/s | 3.7 |
| 2003 | 18.7°C | 15.5°C | 12.3°C | 28.0°C | 9.2°C | 3 mm | 79% | 3 m/s | 4.3 |
| 2002 | 17.9°C | 14.9°C | 11.9°C | 26.4°C | 9.7°C | 2 mm | 79% | 2.8 m/s | 3.8 |
| 2001 | 18.0°C | 15.3°C | 12.6°C | 27.7°C | 10.9°C | 12 mm | 82% | 2.6 m/s | 3.5 |
| 2000 ❄️ | 16.5°C | 14.1°C | 11.8°C | 22.6°C | 9.5°C | 69 mm | 86% | 3.4 m/s | 3.6 |
| 1999 | 18.8°C | 15.6°C | 12.3°C | 25.7°C | 10.4°C | 9 mm | 81% | 2.7 m/s | 3.9 |
| 1998 | 17.9°C | 15.0°C | 12.0°C | 24.2°C | 9.6°C | 25 mm | 80% | 3.5 m/s | 4.2 |
| 1997 | 19.1°C | 16.0°C | 13.0°C | 27.3°C | 10.8°C | 15 mm | 79% | 3.6 m/s | 4.1 |
| 1996 | 17.7°C | 14.7°C | 11.6°C | 28.8°C | 8.2°C | 25 mm | 81% | 3.6 m/s | 3.9 |
| 1995 | 18.8°C | 15.5°C | 12.1°C | 25.7°C | 10.6°C | 3 mm | 78% | 2.8 m/s | 4.1 |
| 1994 | 18.4°C | 15.2°C | 12.1°C | 27.6°C | 8.8°C | 11 mm | 80% | 3.4 m/s | 4.2 |
| 1993 | 19.3°C | 16.2°C | 13.1°C | 25.0°C | 11.6°C | 14 mm | 80% | 2.6 m/s | 3.7 |
| 1992 | 19.7°C | 16.7°C | 13.8°C | 26.9°C | 12.0°C | 32 mm | 83% | 2.6 m/s | 3.8 |
| 1991 | 18.9°C | 15.7°C | 12.6°C | 27.6°C | 8.5°C | 41 mm | 78% | 3.2 m/s | 3.6 |
| 1990 | 19.0°C | 15.4°C | 11.9°C | 26.7°C | 10.3°C | 5 mm | 79% | 3.3 m/s | 4.3 |
| 1989 | 18.4°C | 15.2°C | 12.0°C | 24.7°C | 7.6°C | 38 mm | 82% | 3.3 m/s | 4 |
| 1988 | 17.7°C | 14.8°C | 11.9°C | 25.0°C | 10.1°C | 7 mm | 85% | 2.5 m/s | 2.9 |
| 1987 | 19.9°C | 16.7°C | 13.4°C | 31.4°C | 11.7°C | 19 mm | 79% | 2.2 m/s | 3.4 |
| 1986 | 18.6°C | 15.3°C | 12.0°C | 22.6°C | 10.9°C | 6 mm | 81% | 2.8 m/s | 3.5 |
| 1985 | 18.4°C | 14.9°C | 11.5°C | 29.2°C | 9.1°C | 22 mm | 77% | 3.5 m/s | 3.9 |
| 1984 | 17.4°C | 14.7°C | 11.9°C | 20.7°C | 8.9°C | 49 mm | 82% | 3.7 m/s | 3.8 |
| 1983 | 19.7°C | 17.0°C | 14.2°C | 27.3°C | 12.2°C | 17 mm | 81% | 3.2 m/s | — |
| 1982 | 18.4°C | 15.4°C | 12.4°C | 24.0°C | 10.5°C | 62 mm | 79% | 3.2 m/s | — |
| 1981 | 17.0°C | 14.2°C | 11.4°C | 21.5°C | 9.4°C | 54 mm | 83% | 3.2 m/s | — |
Actual recorded October data for each year, 1981–2025 — sourced from NASA POWER.
The average high in October is around 18.7°C with lows near 12.7°C (mean 15.7°C), based on 45 years of NASA POWER data.
October averages 28 mm of rainfall in San Mateo, one of the drier months. The wettest on record was 141 mm in 2021.
The hottest October reached 31.4°C in 1987. The coldest dipped to 7.6°C in 1989.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average October temperatures have risen by about 1°C. Daytime highs moved from 18.2°C to 19°C and overnight lows from 12.3°C to 13.5°C over the same span.
October is one of the warmer months of the year in San Mateo and one of the drier months, so plan for around 18.7°C daytime highs and 12.7°C at night.
Not quite — October is the 10th coolest month in San Mateo, averaging 15.7°C.
For October in San Mateo, pack light layers you can adjust through the day, with typical highs of 18.7°C and lows of 12.7°C.
Relative humidity in October averages 80% — quite humid.
Average wind speed in October is 3 m/s. The windiest October on record averaged 3.7 m/s (1984).
The wettest October on record was 2021 with 141 mm. On average, October sees 28 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 October, 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 October specifically, along with year-by-year records and how the month has changed over the decades.
