Climate averages 1991–2020
Fontana weather
in August.
A hot, very dry month: the warmest and the driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
August is a hot month in Fontana: daytime highs average 33.5°C and nights cool to about 19.3°C. By daytime temperature it is the warmest month of the year.
Expect about 1.1 mm of rain on fewer than one day, which makes August a very dry month (the driest month of the year). Daylight, from sunrise to sunset, lasts about 13 h 25 min on an average August day.
The nearest other city in this atlas is San Bernardino (13 km away). In August its highs average 33.9°C, about as warm as Fontana, with 9.0 mm of rain.
Among the 498 cities listed in the United States, Fontana ranks 77th of 498 for the warmest August highs and joint 62nd of 498 for the driest August (rainfall, lowest first). The mean August high of those 498 cities is 29.9°C; Fontana is 3.6°C warmer than that mean.
From August to September, average highs fall by 1.9°C to 31.6°C, and monthly rainfall rises from 1.1 mm to 5.5 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
Fontana climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 16.7°C4.3°C | 4.3°C | 96 | 6.6 | 10.210 h |
| February | 17.1°C5.2°C | 5.2°C | 111 | 7.4 | 10.911 h |
| March | 19.3°C6.9°C | 6.9°C | 68 | 6.8 | 12.012 h |
| April | 21.9°C8.8°C | 8.8°C | 32 | 4.6 | 13.013 h |
| May | 24.8°C11.7°C | 11.7°C | 15 | 2.6 | 13.914 h |
| June | 29.0°C15.0°C | 15.0°C | 3.4 | 0.5 | 14.414 h |
| July | 32.4°C18.7°C | 18.7°C | 2.2 | 0.5 | 14.214 h |
| August, selected | 33.5°C19.3°C | 19.3°C | 1.1 | 0.3 | 13.413 h |
| September | 31.6°C17.0°C | 17.0°C | 5.5 | 1.2 | 12.412 h |
| October | 26.3°C12.2°C | 12.2°C | 22 | 3.1 | 11.411 h |
| November | 20.9°C7.5°C | 7.5°C | 30 | 3.5 | 10.410 h |
| December | 16.3°C4.1°C | 4.1°C | 67 | 5.8 | 9.910 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
- San Bernardino in AugustUnited States · 13 kmHigh 33.9°C · Low 20.2°C · 9.0 mm rain
- Rancho Cucamonga in AugustUnited States · 15 kmHigh 33.3°C · Low 19.2°C · 1.1 mm rain
- Riverside in AugustUnited States · 16 kmHigh 33.8°C · Low 19.7°C · 1.1 mm rain
- Ontario in AugustUnited States · 20 kmHigh 32.8°C · Low 19.3°C · 0.9 mm rain
- Redlands in AugustUnited States · 24 kmHigh 34.0°C · Low 20.2°C · 9.0 mm rain
- Chino in AugustUnited States · 25 kmHigh 31.9°C · Low 18.9°C · 0.9 mm rain
- Moreno Valley in AugustUnited States · 26 kmHigh 32.9°C · Low 20.0°C · 9.0 mm rain
- Corona in AugustUnited States · 27 kmHigh 33.2°C · Low 19.3°C · 1.1 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 Fontana) is explained once on the Fontana year overview and on the Sources, method and limits page.
Riverside, Rancho Cucamonga and Corona lie in the same rainfall cell, so their rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.