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Ontario Weather by Month
Average temperatures, rainfall and humidity for Ontario, United States, month by month, built from OpenWeather’s historical records. Use it to see what a typical Ontario month looks like before you travel — then check the live Ontario forecast for the days ahead.
Warmest month
August
33°C average high
Coolest month
January
8°C average low
Wettest month
October
97 mm of rain
Driest month
June
2 mm of rain
Average temperature and rainfall in Ontario by month
Averages of the daily highs and lows recorded in each month, with total rainfall, mean humidity and mean wind speed.
| Month | Avg high | Avg low | Record low / high | Rainfall | Humidity | Wind |
|---|---|---|---|---|---|---|
| January | 19°C | 8°C | -9°C / 30°C | 49 mm | 55% | 9 km/h |
| February | 20°C | 8°C | -5°C / 33°C | 53 mm | 56% | 9 km/h |
| March | 22°C | 9°C | -23°C / 37°C | 40 mm | 59% | 11 km/h |
| April | 24°C | 11°C | -2°C / 36°C | 18 mm | 57% | 11 km/h |
| May | 25°C | 13°C | 3°C / 38°C | 22 mm | 62% | 11 km/h |
| June | 29°C | 16°C | 8°C / 43°C | 2 mm | 59% | 11 km/h |
| July | 32°C | 19°C | 10°C / 43°C | 5 mm | 54% | 11 km/h |
| August | 33°C | 19°C | 9°C / 41°C | 5 mm | 53% | 10 km/h |
| September | 31°C | 18°C | 5°C / 45°C | 8 mm | 55% | 9 km/h |
| October | 27°C | 14°C | 1°C / 40°C | 97 mm | 52% | 8 km/h |
| November | 23°C | 10°C | -4°C / 34°C | 22 mm | 49% | 8 km/h |
| December | 19°C | 8°C | -6°C / 30°C | 53 mm | 56% | 8 km/h |
Best time to visit Ontario
The most comfortable time to visit Ontario is generally April to May and November, balancing mild daytime temperatures against the driest stretch of the year. The city has a moderate seasonal swing and rain concentrates around October, totalling about 373 mm a year.
Travellers who prefer heat should aim for August, when highs average 33°C. October is the month to avoid if rain would spoil your plans — it averages 97 mm, roughly 45× the rainfall of the driest month (June).
Source: OpenWeather historical and statistical weather data. Values are long-term averages, not a forecast — see the Ontario forecast for what is happening now.
Weather across United States right now
- Atlanta30°C
- Austin30°C
- Baltimore28°C
- Boston19°C
- Brooklyn25°C
- Chicago25°C
- Dallas30°C
- Denver30°C
- Detroit20°C
- Houston27°C
- Indianapolis31°C
- Las Vegas33°C
- Los Angeles21°C
- Miami27°C
- Minneapolis27°C
- New York25°C
- Orlando26°C
- Philadelphia25°C
- Phoenix36°C
- Pittsburgh22°C
- Portland15°C
- Queens25°C
- Riverside26°C
- Sacramento21°C
- San Antonio29°C
- San Diego22°C
- San Francisco17°C
- San Jose23°C
- Seattle17°C
- St. Louis32°C
- Tampa25°C
- Washington28°C
