2025 Compare Climate & Weather:
Ontario, CA vs Tucson, AZ

Highlights

On average, there are 286 sunny days per year in Tucson. Ontario averages 279 sunny days per year. The US average is 205 sunny days.

Tucson, Arizona gets 12.3 inches of rain, on average, per year. Ontario, California gets 15.7 inches of rain, on average, per year. The US average is 38.1 inches of rain per year.

Tucson averages 0.4 inches of snow per year. Ontario averages 0 inches of snow per year. The US average is 27.8 inches of snow per year.

Weather Highlights

Tucson, Arizona
Summer High: the July high is around 100.2 degrees
Winter Low: the January low is 38.7
Rain: averages 12.3 inches of rain a year
Snow: averages 0.4 inches of snow a year

Ontario, California
Summer High: the July high is around 91.9 degrees
Winter Low: the January low is 42.6
Rain: averages 15.7 inches of rain a year
Snow: averages 0 inches of snow a year

BestPlaces Comfort Index

The annual BestPlaces Comfort Index for Tucson is 7.5 (10=best), which means it is about average compared to other places in Arizona.

The annual BestPlaces Comfort Index for Ontario is 8.8 (10=best), which means it is more comfortable than most places in California.

Today's Weather - Ontario, CA

59°F

Today's Weather - Tucson, AZ

74°F

Average Monthly High / Low (°F)

Hot, Freezing, Rainy, Snowy Days: Ontario / Tucson

August is the hottest month for Ontario with an average high temperature of 93.4°, which ranks it as warmer than most places in California. In Ontario, there are 5 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Ontario are May, October and April.

June is the hottest month for Tucson with an average high temperature of 100.5°, which ranks it as warmer than most places in Arizona. In Tucson, there are 3 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Tucson are March, November and April.

December has the coldest nighttime temperatures for Ontario with an average of 41.4°. This is warmer than most places in California.

December has the coldest nighttime temperatures for Tucson with an average of 38.0°. This is warmer than most places in Arizona.

In Ontario, there are 79.5 days annually when the high temperature is over 90°, which is hotter than most places in California.

In Tucson, there are 149.2 days annually when the high temperature is over 90°, which is hotter than most places in Arizona.

In Ontario, there are 3.6 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in California.

In Tucson, there are 17.0 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in Arizona.

In Ontario, there are 0.0 days annually when the nighttime low temperature falls below zero°, which is about average compared to other places in California.

In Tucson, there are 0.0 days annually when the nighttime low temperature falls below zero°, which is about average compared to other places in Arizona.

February is the wettest month in Ontario with 3.8 inches of rain, and the driest month is July with 0.0 inches. The wettest season is Spring with 60% of yearly precipitation and 1% occurs in Autumn, which is the driest season. The annual rainfall of 15.7 inches in Ontario means that it is drier than most places in California.


August is the wettest month in Tucson with 2.4 inches of rain, and the driest month is May with 0.2 inches. The wettest season is Autumn with 40% of yearly precipitation and 11% occurs in Summer, which is the driest season. The annual rainfall of 12.3 inches in Tucson means that it is about average compared to other places in Arizona.

February is the rainiest month in Ontario with 5.7 days of rain, and July is the driest month with only 0.2 rainy days. There are 30.5 rainy days annually in Ontario, which is one of the least rainy places in California. The rainiest season is Spring when it rains 50% of the time and the driest is Autumn with only a 4% chance of a rainy day.

August is the rainiest month in Tucson with 9.5 days of rain, and June is the driest month with only 1.4 rainy days. There are 51.5 rainy days annually in Tucson, which is about average compared to other places in Arizona. The rainiest season is Autumn when it rains 38% of the time and the driest is Summer with only a 15% chance of a rainy day.

There is rarely any recorded snowfall in Ontario, ranking it as one of the least snowy places in California.

An annual snowfall of 0.4 inches in Tucson means that it is about average compared to other places in Arizona.

Any measurable snowfall is a rare occurance in Ontario.

January is the snowiest month in Tucson with 0.2 inches of snow, and no months of the year have significant snowfall.