2025 Compare Climate & Weather:
Flagstaff, AZ vs Boulder, CO

Highlights

On average, there are 245 sunny days per year in Boulder. Flagstaff averages 266 sunny days per year. The US average is 205 sunny days.

Boulder, Colorado gets 18.1 inches of rain, on average, per year. Flagstaff, Arizona gets 20.7 inches of rain, on average, per year. The US average is 38.1 inches of rain per year.

Boulder averages 71.1 inches of snow per year. Flagstaff averages 81 inches of snow per year. The US average is 27.8 inches of snow per year.

Weather Highlights

Boulder, Colorado
Summer High: the July high is around 88.1 degrees
Winter Low: the January low is 18.9
Rain: averages 18.1 inches of rain a year
Snow: averages 71.1 inches of snow a year

Flagstaff, Arizona
Summer High: the July high is around 81.7 degrees
Winter Low: the January low is 14.3
Rain: averages 20.7 inches of rain a year
Snow: averages 81 inches of snow a year

BestPlaces Comfort Index

The annual BestPlaces Comfort Index for Boulder is 7.1 (10=best), which means it is about average compared to other places in Colorado.

The annual BestPlaces Comfort Index for Flagstaff is 6.9 (10=best), which means it is one of the least comfortable places in Arizona.

Today's Weather - Flagstaff, AZ

33°F

Today's Weather - Boulder, CO

47°F

Average Monthly High / Low (°F)

Hot, Freezing, Rainy, Snowy Days: Flagstaff / Boulder

July is the hottest month for Flagstaff with an average high temperature of 81.7°, which ranks it as one of the coolest places in Arizona. In Flagstaff, there are 4 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Flagstaff are June, August and July.

July is the hottest month for Boulder with an average high temperature of 88.1°, which ranks it as about average compared to other places in Colorado. In Boulder, there are 3 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Boulder are September, June and May.

January has the coldest nighttime temperatures for Flagstaff with an average of 14.3°. This is one of the coldest places in Arizona.

December has the coldest nighttime temperatures for Boulder with an average of 18.3°. This is one of the warmest places in Colorado.

In Flagstaff, there are 3.4 days annually when the high temperature is over 90°, which is one of the coolest places in Arizona.

In Boulder, there are 32.4 days annually when the high temperature is over 90°, which is about average compared to other places in Colorado.

In Flagstaff, there are 210.5 days annually when the nighttime low temperature falls below freezing, which is one of the coldest places in Arizona.

In Boulder, there are 151.2 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in Colorado.

In Flagstaff, there are 7.8 days annually when the nighttime low temperature falls below zero°, which is one of the coldest places in Arizona.

In Boulder, there are 5.5 days annually when the nighttime low temperature falls below zero°, which is warmer than most places in Colorado.

August is the wettest month in Flagstaff with 3.3 inches of rain, and the driest month is June with 0.3 inches. The wettest season is Autumn with 29% of yearly precipitation and 17% occurs in Summer, which is the driest season. The annual rainfall of 20.7 inches in Flagstaff means that it is wetter than most places in Arizona.


May is the wettest month in Boulder with 2.5 inches of rain, and the driest month is January with 0.6 inches. The wettest season is Summer with 37% of yearly precipitation and 11% occurs in Spring, which is the driest season. The annual rainfall of 18.1 inches in Boulder means that it is wetter than most places in Colorado.

August is the rainiest month in Flagstaff with 13.8 days of rain, and June is the driest month with only 2.8 rainy days. There are 83.4 rainy days annually in Flagstaff, which is one of the rainiest places in Arizona. The rainiest season is Autumn when it rains 34% of the time and the driest is Summer with only a 20% chance of a rainy day.

May is the rainiest month in Boulder with 10.5 days of rain, and January is the driest month with only 4.7 rainy days. There are 88.0 rainy days annually in Boulder, which is rainier than most places in Colorado. The rainiest season is Autumn when it rains 31% of the time and the driest is Spring with only a 17% chance of a rainy day.

An annual snowfall of 81.0 inches in Flagstaff means that it is one of the snowiest places in Arizona.

An annual snowfall of 71.1 inches in Boulder means that it is snowier than most places in Colorado.

January is the snowiest month in Flagstaff with 19.1 inches of snow, and 8 months of the year have significant snowfall.

March is the snowiest month in Boulder with 14.3 inches of snow, and 9 months of the year have significant snowfall.