Climate averages 1991–2020
San Mateo weather
in August.
A warm, very dry month: the 2nd warmest and the 2nd driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
August is a warm month in San Mateo: daytime highs average 23.6°C and nights cool to about 14.2°C. By daytime temperature it is the 2nd warmest of the 12 months.
Rain is very rare: less than 1 mm falls in a typical August (the 2nd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 37 min on an average August day.
The nearest other city in this atlas is Redwood City (12 km away). In August its highs average 24.5°C, 0.9°C warmer than San Mateo, with almost no rain (under 1 mm).
Among the 498 cities listed in the United States, San Mateo ranks joint 490th of 498 for the warmest August highs and joint 29th of 498 for the driest August (rainfall, lowest first). The mean August high of those 498 cities is 29.9°C; San Mateo is 6.3°C cooler than that mean.
From August to September, average highs rise by 0.4°C to 24.0°C, and monthly rainfall rises from under 1 mm to 1.8 mm.
The annual picture
August in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
San Mateo climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 13.9°C6.7°C | 6.7°C | 99 | 9.4 | 9.910 h |
| February | 14.8°C7.5°C | 7.5°C | 107 | 9.5 | 10.811 h |
| March | 16.1°C8.5°C | 8.5°C | 82 | 9.1 | 11.912 h |
| April | 17.4°C9.3°C | 9.3°C | 41 | 5.6 | 13.113 h |
| May | 19.3°C10.9°C | 10.9°C | 20 | 3.3 | 14.214 h |
| June | 21.8°C12.4°C | 12.4°C | 3.9 | 0.9 | 14.715 h |
| July | 23.2°C13.7°C | 13.7°C | 0.5 | 0.2 | 14.514 h |
| August, selected | 23.6°C14.2°C | 14.2°C | 0.7 | 0.1 | 13.614 h |
| September | 24.0°C14.2°C | 14.2°C | 1.8 | 0.4 | 12.512 h |
| October | 21.7°C12.9°C | 12.9°C | 23 | 3.0 | 11.311 h |
| November | 17.0°C9.9°C | 9.9°C | 51 | 6.0 | 10.210 h |
| December | 13.7°C7.2°C | 7.2°C | 94 | 9.3 | 9.610 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
August in nearby cities
- Redwood City in AugustUnited States · 12 kmHigh 24.5°C · Low 14.4°C · 0.7 mm rain
- Daly City in AugustUnited States · 20 kmHigh 19.6°C · Low 12.8°C · 0.7 mm rain
- Hayward in AugustUnited States · 25 kmHigh 26.7°C · Low 14.5°C · 1.4 mm rain
- San Francisco in AugustUnited States · 25 kmHigh 22.1°C · Low 13.2°C · 0.7 mm rain
- Union City in AugustUnited States · 27 kmHigh 28.0°C · Low 15.1°C · 1.0 mm rain
- Oakland in AugustUnited States · 27 kmHigh 26.3°C · Low 14.2°C · 0.9 mm rain
- Mountain View in AugustUnited States · 29 kmHigh 26.3°C · Low 14.8°C · 1.0 mm rain
- Fremont in AugustUnited States · 30 kmHigh 27.6°C · Low 15.2°C · 1.0 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for San Mateo) is explained once on the San Mateo year overview and on the Sources, method and limits page.
Redwood City lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.