2025 Compare Climate & Weather:
Boulder, CO vs Charleston, SC

Highlights

On average, there are 209 sunny days per year in Charleston. Boulder averages 245 sunny days per year. The US average is 205 sunny days.

Charleston, South Carolina gets 48.3 inches of rain, on average, per year. Boulder, Colorado gets 18.1 inches of rain, on average, per year. The US average is 38.1 inches of rain per year.

Charleston averages 0.4 inches of snow per year. Boulder averages 71.1 inches of snow per year. The US average is 27.8 inches of snow per year.

Weather Highlights

Charleston, South Carolina
Summer High: the July high is around 89.9 degrees
Winter Low: the January low is 39.3
Rain: averages 48.3 inches of rain a year
Snow: averages 0.4 inches of snow a year

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

BestPlaces Comfort Index

The annual BestPlaces Comfort Index for Charleston is 7.2 (10=best), which means it is less comfortable than most places in South Carolina.

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

Today's Weather - Boulder, CO

50°F

Today's Weather - Charleston, SC

66°F

Average Monthly High / Low (°F)

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

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.

July is the hottest month for Charleston with an average high temperature of 89.9°, which ranks it as cooler than most places in South Carolina. In Charleston, there are 4 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Charleston are October, May and April.

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

January has the coldest nighttime temperatures for Charleston with an average of 39.3°. This is one of the warmest places in South Carolina.

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 Charleston, there are 41.1 days annually when the high temperature is over 90°, which is cooler than most places in South Carolina.

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 Charleston, there are 17.5 days annually when the nighttime low temperature falls below freezing, which is one of the warmest places in South Carolina.

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

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

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 wettest month in Charleston with 6.7 inches of rain, and the driest month is May with 2.5 inches. The wettest season is Autumn with 36% of yearly precipitation and 19% occurs in Summer, which is the driest season. The annual rainfall of 48.3 inches in Charleston means that it is wetter than most places in South Carolina.

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.

August is the rainiest month in Charleston with 11.7 days of rain, and May is the driest month with only 6.8 rainy days. There are 105.9 rainy days annually in Charleston, which is rainier than most places in South Carolina. The rainiest season is Autumn when it rains 32% of the time and the driest is Summer with only a 21% chance of a rainy day.

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

An annual snowfall of 0.4 inches in Charleston means that it is less snowy than most places in South Carolina.

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

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