Ontario Climate by Month
Ontario, California, United States
Hot summers and mild winters, with little rain, mostly from December to March.
The climate in Ontario is one of hot summers and mild winters, with little rain, mostly from December to March. August is the warmest month, with highs around 92°F (34°C); December is the coolest at 68°F (20°C), and nights dip to 42°F (5°C). It gets only 14 in (345 mm) of rain a year. May to September are almost completely dry.
- Warmest month
- 92°F(34°C)
- Average high, August
- Coldest nights
- 42°F(5°C)
- Average low, December
- Rain per year
- 14 in(345 mm)
- Wettest: February
- Humidity
- 48%
- Sunniest: June
Best and worst months in Ontario
Best for weatherApril, May and November are the best time for weather in Ontario: highs near 77°F (25°C) and about 0.8 in (21 mm) of rain a month.
Least pleasantJuly and August are the least pleasant; August is the hottest, with highs of 92°F (34°C).
Comfort combines how close the afternoon high is to 75°F (24°C) with how much rain falls and how humid it is. See where the weather is best in November.
Temperature and rain through the year
Highs and lows (°F)
Average highAverage low
Rain (in per month)
Ontario weather by month
| Month | High | Low | Rain | Humidity | Sun |
|---|---|---|---|---|---|
| JanJanuary | 68°F(20°C) | 43°F(6°C) | 2.8 in(72 mm) | 46% | 2.9 |
| FebFebruary | 69°F(20°C) | 44°F(7°C) | 3.1 in(80 mm) | 52% | 3.4 |
| MarMarch | 71°F(22°C) | 46°F(8°C) | 2.0 in(52 mm) | 53% | 4.9 |
| AprAprilBest | 76°F(25°C) | 49°F(9°C) | 1.1 in(28 mm) | 47% | 5.9 |
| MayMayBest | 79°F(26°C) | 54°F(12°C) | 0.3 in(7 mm) | 50% | 6.5 |
| JunJune | 85°F(29°C) | 58°F(14°C) | 0.0 in(1 mm) | 50% | 7.0 |
| JulJuly | 91°F(33°C) | 62°F(17°C) | 0.0 in(1 mm) | 49% | 6.9 |
| AugAugust | 92°F(34°C) | 63°F(17°C) | 0.0 in(1 mm) | 46% | 6.6 |
| SepSeptember | 90°F(32°C) | 60°F(16°C) | 0.2 in(4 mm) | 44% | 5.6 |
| OctOctober | 83°F(28°C) | 54°F(12°C) | 0.5 in(12 mm) | 42% | 4.2 |
| NovNovemberBest | 75°F(24°C) | 47°F(8°C) | 1.1 in(29 mm) | 44% | 3.3 |
| DecDecember | 68°F(20°C) | 42°F(5°C) | 2.3 in(58 mm) | 48% | 2.6 |
1991–2020 averages. Sun is solar radiation in kWh/m² per day. Highlighted: the most comfortable months.
Places with a similar climate outside the United States
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