2025 Compare Climate & Weather:
Crystal Lake, IL vs Boulder, CO

Highlights

On average, there are 245 sunny days per year in Boulder. Crystal Lake averages 186 sunny days per year. The US average is 205 sunny days.

Boulder, Colorado gets 18.1 inches of rain, on average, per year. Crystal Lake, Illinois gets 36.7 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. Crystal Lake averages 35.1 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

Crystal Lake, Illinois
Summer High: the July high is around 81.8 degrees
Winter Low: the January low is 12.7
Rain: averages 36.7 inches of rain a year
Snow: averages 35.1 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 Crystal Lake is 6.8 (10=best), which means it is less comfortable than most places in Illinois.

Today's Weather - Crystal Lake, IL

75°F

Today's Weather - Boulder, CO

45°F

Average Monthly High / Low (°F)

Hot, Freezing, Rainy, Snowy Days: Crystal Lake / Boulder

July is the hottest month for Crystal Lake with an average high temperature of 81.8°, which ranks it as one of the coolest places in Illinois. In Crystal Lake, there are 4 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Crystal Lake 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 Crystal Lake with an average of 12.7°. This is one of the coldest places in Illinois.

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

In Crystal Lake, there are 6.9 days annually when the high temperature is over 90°, which is one of the coolest places in Illinois.

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 Crystal Lake, there are 138.7 days annually when the nighttime low temperature falls below freezing, which is one of the coldest places in Illinois.

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 Crystal Lake, there are 11.6 days annually when the nighttime low temperature falls below zero°, which is colder than most places in Illinois.

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 Crystal Lake with 4.4 inches of rain, and the driest month is January with 1.7 inches. The wettest season is Autumn with 34% of yearly precipitation and 15% occurs in Spring, which is the driest season. The annual rainfall of 36.7 inches in Crystal Lake means that it is drier than most places in Illinois.


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.

May is the rainiest month in Crystal Lake with 11.6 days of rain, and February is the driest month with only 7.6 rainy days. There are 114.2 rainy days annually in Crystal Lake, which is rainier than most places in Illinois. The rainiest season is Summer when it rains 27% of the time and the driest is Spring with only a 23% 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 35.1 inches in Crystal Lake means that it is one of the snowiest places in Illinois.

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 Crystal Lake with 10.9 inches of snow, and 6 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.