August weather in Ontario, CA
The average temperature in Ontario in August is 80.1°F (65.2°F–94.9°F). Average precipitation: 0.03 inches.
August is a summer month in Ontario, and is warmer than the annual average of 66.8°F. Daily temperatures swing about 29.7°F between overnight low and afternoon high. Expect about 0 days with precipitation. Daylight averages about 13h 16m. For travel, August is hot.
Avg High
94.9°F
Avg Low
65.2°F
Precipitation
0.03 in
Daylight
13h 16m
August records in Ontario
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| August 1 | 104.0°F (2017) | 57.9°F (2010) | 0.00 in (1998) |
| August 2 | 104.0°F (2021) | 57.9°F (2013) | 0.09 in (2014) |
| August 3 | 105.1°F (1998) | 59.0°F (2013) | 0.04 in (2014) |
| August 4 | 104.0°F (1998) | 57.9°F (2002) | 0.00 in (1998) |
| August 5 | 107.1°F (2024) | 57.9°F (2010) | 0.00 in (1998) |
| August 6 | 107.1°F (2012) | 57.0°F (2010) | 0.00 in (1998) |
| August 7 | 104.0°F (2012) | 57.0°F (1999) | 0.00 in (1998) |
| August 8 | 104.0°F (2012) | 55.9°F (1999) | 0.00 in (1998) |
| August 9 | 104.0°F (2012) | 55.9°F (2010) | 0.00 in (1998) |
| August 10 | 104.0°F (2012) | 57.9°F (1999) | 0.02 in (1998) |
| August 11 | 105.1°F (2012) | 57.0°F (1999) | 0.00 in (1998) |
| August 12 | 105.1°F (2012) | 57.0°F (2010) | 0.00 in (1998) |
| August 13 | 105.1°F (2012) | 59.0°F (2010) | 0.00 in (1998) |
| August 14 | 105.1°F (2003) | 57.0°F (2010) | 0.00 in (1998) |
| August 15 | 109.9°F (2020) | 57.9°F (1999) | 0.30 in (2005) |
| August 16 | 107.1°F (2015) | 57.9°F (1999) | 0.00 in (1998) |
| August 17 | 102.0°F (2023) | 57.9°F (2009) | 0.00 in (1998) |
| August 18 | 108.0°F (2020) | 59.0°F (2005) | 0.00 in (1998) |
| August 19 | 107.1°F (2020) | 59.0°F (2005) | 0.00 in (1998) |
| August 20 | 104.0°F (2020) | 59.0°F (2005) | 1.69 in (2023) |
| August 21 | 102.9°F (2020) | 57.0°F (2011) | 0.23 in (2023) |
| August 22 | 104.0°F (1998) | 59.0°F (2002) | 0.00 in (1998) |
| August 23 | 105.1°F (1998) | 57.9°F (2004) | 0.00 in (1998) |
| August 24 | 106.0°F (2010) | 57.9°F (2004) | 0.00 in (1998) |
| August 25 | 108.0°F (2010) | 60.1°F (2004) | 0.00 in (1998) |
| August 26 | 104.0°F (2010) | 59.0°F (2006) | 0.00 in (1998) |
| August 27 | 108.0°F (2009) | 60.1°F (2002) | 0.00 in (1998) |
| August 28 | 109.9°F (2017) | 59.0°F (2002) | 0.00 in (1998) |
| August 29 | 108.0°F (1998) | 57.9°F (2002) | 0.01 in (2000) |
| August 30 | 109.0°F (1998) | 57.0°F (2010) | 0.00 in (1998) |
| August 31 | 111.9°F (2017) | 55.9°F (1999) | 0.13 in (1998) |