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.

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Sun hours / year

3,804

Sunniest month

May

Peak score

99/100

Rain / year

290 mm

Midday UV at peak

10 (very high)

Population

175k

Elevation

283 m

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

See Ontario on the interactive sunshine globe →

Nearby places for sunshine

• Los Angeles United States · 75 km · best in Jun · 3,009 h sun/yr
• Palm Springs United States · 104 km · best in Apr · 3,777 h sun/yr
• San Diego United States · 152 km · best in Jul · 2,854 h sun/yr
• Tijuana Mexico · 178 km · best in May · 3,734 h sun/yr
• Santa Barbara United States · 210 km · best in Jul · 3,525 h sun/yr
• Mexicali Mexico · 270 km · best in Mar · 3,841 h sun/yr

Nearest destinations

• San Bernardino United States · 34 km · 3,804 h sun/yr · best in Jun
• Hawthorne United States · 69 km · 3,009 h sun/yr · best in Jun

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