Ontario weather in August: Ontario, California: normal highs, lows, rain and records for August
Ontario in August has a normal high of 95°F and a normal low of 65°F, a daily mean of 80°F, holding near 95°F all month. Measurable precipitation falls on 0 days in a normal August, 0.03 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 35°C and low of 18°C, 1 mm of precipitation in August.
- NOAA stationOntario International Airport
- Station IDUSW00003102
- Location34.06°N 117.60°W
- Elevation949 ft (289 m)
- From the center1 miles
- Population185,285
- Jan 68° 45°
- Feb 68° 46°
- Mar 72° 49°
- Apr 76° 51°
- May 80° 56°
- Jun 86° 60°
- Jul 94° 65°
- Aug 95° 65°
- Sep 91° 64°
- Oct 83° 57°
- Nov 75° 49°
- Dec 67° 44°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Ontario in August?
The normal high is 95°F and the normal low 65°F, for a daily mean of 80.1°F. August is 0.9°F warmer than July and 2.5°F warmer than September. August is the warmest month of the year in Ontario and the 11th wettest. From one year to the next August's mean temperature typically moves about 1.7°F either way (NOAA's standard deviation), so roughly two Augusts in three average between 78°F and 82°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 2%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| August 1 | 95°F | 65°F | 2% | 0% |
| August 8 | 95°F | 65°F | 1% | 0% |
| August 15 | 95°F | 65°F | 1% | 0% |
| August 22 | 95°F | 65°F | 1% | 0% |
| August 31 | 95°F | 65°F | 2% | 1% |
Every day of August: normal high, low and chance of precipitation (warmest afternoon August 20, coldest night August 4)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| August 1 | 95°F | 65°F | 2% | 0% | 13 h 50 min |
| August 2 | 95°F | 65°F | 2% | 0% | 13 h 50 min |
| August 3 | 95°F | 65°F | 2% | 0% | 13 h 50 min |
| August 4 | 95°F | 65°F | 2% | 0% | 13 h 50 min |
| August 5 | 95°F | 65°F | 1% | 0% | 13 h 50 min |
| August 6 | 95°F | 65°F | 1% | 0% | 13 h 40 min |
| August 7 | 95°F | 65°F | 1% | 0% | 13 h 40 min |
| August 8 | 95°F | 65°F | 1% | 0% | 13 h 40 min |
| August 9 | 95°F | 65°F | 1% | 0% | 13 h 40 min |
| August 10 | 95°F | 65°F | 1% | 0% | 13 h 40 min |
| August 11 | 95°F | 65°F | 1% | 0% | 13 h 30 min |
| August 12 | 95°F | 65°F | 1% | 0% | 13 h 30 min |
| August 13 | 95°F | 65°F | 1% | 0% | 13 h 30 min |
| August 14 | 95°F | 65°F | 1% | 0% | 13 h 30 min |
| August 15 | 95°F | 65°F | 1% | 0% | 13 h 30 min |
| August 16 | 95°F | 65°F | 1% | 0% | 13 h 30 min |
| August 17 | 95°F | 65°F | 1% | 0% | 13 h 20 min |
| August 18 | 95°F | 65°F | 1% | 0% | 13 h 20 min |
| August 19 | 95°F | 65°F | 1% | 0% | 13 h 20 min |
| August 20 | 95°F | 65°F | 1% | 0% | 13 h 20 min |
| August 21 | 95°F | 65°F | 1% | 0% | 13 h 20 min |
| August 22 | 95°F | 65°F | 1% | 0% | 13 h 10 min |
| August 23 | 95°F | 65°F | 1% | 0% | 13 h 10 min |
| August 24 | 95°F | 65°F | 1% | 0% | 13 h 10 min |
| August 25 | 95°F | 65°F | 1% | 1% | 13 h 10 min |
| August 26 | 95°F | 65°F | 1% | 1% | 13 h 10 min |
| August 27 | 95°F | 65°F | 2% | 1% | 13 h |
| August 28 | 95°F | 65°F | 2% | 1% | 13 h |
| August 29 | 95°F | 65°F | 2% | 1% | 13 h |
| August 30 | 95°F | 65°F | 2% | 1% | 13 h |
| August 31 | 95°F | 65°F | 2% | 1% | 13 h |
- Normal high
- 95°FAugust average
- Normal low
- 65°FAugust average
- Precipitation
- 0.03 inmonth total
- Days with precipitation
- fewer than 10.01 inch or more
- Days at 90°F or more
- 24
- Daylight
- 13 h 50 min to 13 hAugust 1 to August 31
- Days at 70°F or more
- 31
- Days at 80°F or more
- 31
- Sunshine
- 96%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00003102; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Ontario in August?
On a given August day the chance of 0.01 inch or more is 1% on average, highest around August 30 (2%). In all, 0.03 in falls on 0 days of a normal August.
In a normal August in Ontario, 24 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00003102.
What are the records for August in Ontario?
The warmest August temperature on this station's record (since 1998) is 112°F, on August 31, 2017; the coldest is 56°F, on August 31, 1999. The wettest August brought 1.92 in (2023).
The August mean against the 1991-2020 normal of 80.1°F: 2021 81.8°F (+1.7), 2022 82.7°F (+2.6), 2023 80.5°F (+0.4), 2024 81.0°F (+1.0), 2025 81.1°F (+1.0), 2026 84.5°F (+4.4). 6 of 6 ran warmer than normal.
| August | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 81.8°F | +1.7°F | 0.00 in |
| 2022 | 82.7°F | +2.6°F | 0.00 in |
| 2023 | 80.5°F | +0.4°F | 1.92 in |
| 2024 | 81.0°F | +1.0°F | 0.00 in |
| 2025 | 81.1°F | +1.0°F | 0.00 in |
| 2026 | 84.5°F | +4.4°F | 0.00 in |
Source: records: ACIS, station USW00003102; recent months: ACIS, station USW00003102. Records and recent months use complete months only.
How does August in Ontario compare across California?
Across the 219 places PlainClimate covers in California, August normal highs run from 63°F in Bodega to 109°F in Needles; Ontario's is 95°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.