Ontario weather by month & the best time to visit
United States · regional city · semi-arid climate
The best time to visit Ontario is May — its sunniest month (Sunshine Score 99/100), with April and October close behind. Ontario averages about 3,804 hours of sunshine a year. Daytime highs around 28°C / 82°F and roughly 7 mm of rain in May.
When is the best time to visit Ontario?
For sunshine, the best time to visit Ontario is May, then April and October. The dullest month is July (59/100, 5 mm of rain). The full month-by-month picture is in the table below.
How sunny is Ontario?
Ontario is one of the sunniest places on Earth: about 3,804 hours of sunshine a year. May (99/100) is noticeably better than July (59). It ranks #6 of 580 destinations in United States for annual sunshine, above the national median of 2,279 hours. Rain is strongly seasonal here: roughly 62% of the year's 290 mm falls in the three months around January.
Sunshine Score by month
| Month | Score | Day high | Night low | Rain | UV |
|---|---|---|---|---|---|
| January | 82 | 19° / 66°F | 6° / 43°F | 58 mm | 3 |
| February | 88 | 20° / 68°F | 7° / 45°F | 63 mm | 4 |
| March | 94 | 22° / 72°F | 8° / 46°F | 32 mm | 6 |
| April | 97 | 25° / 77°F | 10° / 50°F | 18 mm | 7 |
| May | 99 | 28° / 82°F | 13° / 55°F | 7 mm | 8 |
| June | 90 | 33° / 91°F | 16° / 61°F | 1 mm | 10 |
| July | 59 | 36° / 97°F | 20° / 68°F | 5 mm | 10 |
| August | 60 | 36° / 97°F | 20° / 68°F | 3 mm | 9 |
| September | 79 | 34° / 93°F | 19° / 66°F | 5 mm | 8 |
| October | 97 | 29° / 84°F | 14° / 57°F | 16 mm | 5 |
| November | 96 | 23° / 73°F | 10° / 50°F | 24 mm | 4 |
| December | 74 | 18° / 64°F | 6° / 43°F | 58 mm | 2 |
Nearest destinations
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Head-to-head
How Ontario compares month by month: Ontario vs Los Angeles · Ontario vs San Diego · Ontario vs Santa Barbara · Ontario vs Palm Springs · all comparisons
Ontario: questions and answers
What kind of destination is Ontario?
Ontario is a regional city in United States with a semi-arid climate.
How many hours of sunshine does Ontario get a year?
Ontario gets about 3,804 hours of sunshine a year, at its best around May.
When is the best time to visit Ontario?
The sunniest time to visit Ontario is May, when the Sunshine Score peaks at 99/100 (with April and October close behind). Expect daytime highs around 28°C / 82°F.
What is the least sunny month in Ontario?
July is the least sunny month in Ontario, scoring 59/100 with about 5 mm of rain.
How strong is the sun in Ontario?
The typical midday UV index in Ontario peaks around 10 (very high) in June, easing to about 2 (low) in December. Month-by-month midday UV values are in the UV column of the table on this page.
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