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Ontario, CA Weather


Ontario, CA climate is warm during summer when temperatures tend to be in the 70's and cool during winter when temperatures tend to be in the 50's.

The warmest month of the year is August with an average maximum temperature of 89.20 degrees Fahrenheit, while the coldest month of the year is December with an average minimum temperature of 41.00 degrees Fahrenheit.

Temperature variations between night and day tend to be relatively big during summer with a difference that can reach 30 degrees Fahrenheit, and moderate during winter with an average difference of 26 degrees Fahrenheit.

The annual average precipitation at Ontario is 16.96 Inches. Winter months tend to be wetter than summer months. The wettest month of the year is February with an average rainfall of 4.05 Inches.

Weather Data

Normal Climate

Normal Temperatures

(POMONA FAIRPLEX Weather station, 6.97 miles from Ontario)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Max °F 67.6 69.0 69.1 74.1 76.7 82.3 88.7 89.2 86.7 80.2 73.1 68.3 77.1
Mean °F 54.6 56.3 56.9 60.5 64.1 68.7 73.8 74.2 72.4 66.4 59.3 54.7 63.5
Min °F 41.5 43.5 44.6 46.9 51.5 55.1 58.8 59.2 58.0 52.6 45.4 41.0 49.8

Normal Precipitation

(POMONA FAIRPLEX Weather station, 6.97 miles from Ontario)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Inch 4.02 4.05 3.45 0.73 0.25 0.05 0.00 0.13 0.29 0.66 1.29 2.04 16.96