San Mateo has a warm temperate climate with warm summers and mild winters.
Temperatures peak in September and drop to their lowest in January, while rainfall is highest during winter months.
Humidity remains high throughout the year creating warm and humid conditions.
| Month | 🌤️ | Avg High | Avg Temp | Avg Low | Record High | Record Low | Humid % | Rain (mm) | Wind (m/s) | Solar (kWh/m²) |
|---|---|---|---|---|---|---|---|---|---|---|
| January | ☔ | 56.0°F | 51.7°F | 47.4°F | 67.1°F | 35.2°F | 83% | 99 | 3.6 | 2.42 |
| February | ☔ | 56.7°F | 52.5°F | 48.3°F | 70.9°F | 31.3°F | 83% | 93 | 3.8 | 3.31 |
| March | ☔ | 57.4°F | 53.2°F | 49.0°F | 76.5°F | 41.0°F | 83% | 80 | 3.9 | 4.62 |
| April | 🌤️ | 58.4°F | 54.0°F | 49.5°F | 79.7°F | 41.2°F | 83% | 32 | 4.0 | 6.02 |
| May | 🌤️ | 59.8°F | 55.5°F | 51.1°F | 87.4°F | 44.6°F | 85% | 17 | 4.1 | 6.74 |
| June | 🌤️ | 62.0°F | 57.5°F | 53.0°F | 88.2°F | 47.8°F | 85% | 7 | 3.9 | 7.12 |
| July | ☀️ | 63.3°F | 59.0°F | 54.8°F | 81.7°F | 49.6°F | 86% | 2 | 3.4 | 6.53 |
| August | ☀️ | 65.1°F | 60.7°F | 56.3°F | 85.3°F | 51.3°F | 85% | 3 | 3.3 | 5.85 |
| September | ☀️ | 66.8°F | 61.7°F | 56.6°F | 93.9°F | 50.5°F | 83% | 7 | 3.0 | 5.04 |
| October | ☀️ | 65.6°F | 60.2°F | 54.8°F | 88.5°F | 45.7°F | 80% | 28 | 3.0 | 3.90 |
| November | 🌤️ | 60.6°F | 55.8°F | 51.1°F | 79.2°F | 37.4°F | 80% | 62 | 3.3 | 2.83 |
| December | ☔ | 56.2°F | 51.9°F | 47.7°F | 68.9°F | 31.5°F | 82% | 102 | 3.8 | 2.18 |
Showing average climate conditions across 45 years (1981–2025)
🧥 Light layers are sufficient — this Mild Winter stays cool without prolonged hard freezes.
🌤️ Conditions are ideal for outdoor activities throughout the day in this Mild Summer.
☔ Moderate Rainfall expected — carry rain gear and plan outdoor activities around these months.
Monthly averages · 1981–2025 climate normals · °F
Temperatures rise steadily from spring, peak in September, and gradually decline through autumn into winter.
These seasonal patterns offer comfortable conditions year-round, with warm summers and mild winters.
Monthly rainfall · 1981–2025 seasonal trends · mm/month
Rainfall is concentrated in the winter months. Humidity stays high (around 83%), peaking during summer months, which creates warm and humid conditions.
☔ Moderate Rainfall expected — carry rain gear and plan outdoor activities around these months.
Monthly averages · 1981–2025
Across 45 years of records, San Mateo's temperature shows a slight warming trend over the past decade. Its hottest day reached 93.9°F in September 2017, and its coldest dropped to 31.3°F in February 1989. 2014 was the warmest year overall and 1999 the coolest.
The warmest year in San Mateo's recorded history was 2014 (avg: 58.6°F), while the coldest was 1999 (avg: 54.3°F).
Average annual high/low · Last 30 years · °F
Total annual precipitation · Last 30 years · mm/year
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall (mm) | Avg Humidity | Avg Wind |
|---|---|---|---|---|---|---|---|---|
2025 | 60.8°F | 56.7°F | 52.5°F | 83.8°F | 43.2°F | 473 | 86% | 3.5 m/s |
2024 | 61.3°F | 57.0°F | 52.9°F | 87.8°F | 43.5°F | 633 | 85% | 3.6 m/s |
2023 | 60.3°F | 56.1°F | 52.0°F | 84.2°F | 40.5°F | 713 | 84% | 3.7 m/s |
2022 | 60.8°F | 56.3°F | 51.6°F | 82.4°F | 40.8°F | 392 | 83% | 3.5 m/s |
2021 | 60.3°F | 55.9°F | 51.6°F | 77.7°F | 41.4°F | 538 | 84% | 3.7 m/s |
2020 | 61.9°F | 57.2°F | 52.5°F | 85.3°F | 41.4°F | 225 | 82% | 3.4 m/s |
2019 | 61.7°F | 57.4°F | 53.1°F | 86.7°F | 41.9°F | 696 | 82% | 3.7 m/s |
2018 | 61.3°F | 56.8°F | 52.5°F | 75.4°F | 41.2°F | 464 | 82% | 3.5 m/s |
2017 | 61.7°F | 57.2°F | 52.7°F | 93.9°F | 38.8°F | 711 | 82% | 3.6 m/s |
2016 | 61.3°F | 57.2°F | 53.1°F | 86.2°F | 39.6°F | 635 | 85% | 3.5 m/s |
Showing 1 to 10 of 45 years
Based on 45 years of data (1981–2025), September is typically the hottest month in San Mateo, California, with average high temperatures around 66.8°F.
January is the coldest month in San Mateo, with average low temperatures around 47.4°F.
December receives the most rainfall with approximately 102 mm, while July is the driest with 2 mm.
The highest recorded temperature was 93.9°F in September 2017. This is part of the historical record spanning 1981–2025.
The lowest recorded temperature was 31.3°F in February 1989.
This page covers 45 years of climate data from 1981 to 2025. As new data is added to the database the page automatically reflects the updated coverage.
San Mateo receives the most sunlight in June with an average solar radiation of 7.12 kWh/m²/day. This solar radiation data, sourced from NASA POWER, is useful for solar energy planning and agriculture in California.
All climate data is sourced from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite and model data. It provides monthly averages for temperature, precipitation, humidity, wind speed, and solar radiation.
All weather data is sourced from NASA POWER (Prediction of Worldwide Energy Resources), a NASA project providing solar and meteorological data for renewable energy, building efficiency, and agricultural research.
