2025 Compare Climate & Weather:
Boulder, CO vs St. Louis, MO

Highlights

On average, there are 202 sunny days per year in St. Louis. Boulder averages 245 sunny days per year. The US average is 205 sunny days.

St. Louis, Missouri gets 42.2 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.

St. Louis averages 15.5 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

St. Louis, Missouri
Summer High: the July high is around 88.5 degrees
Winter Low: the January low is 22.8
Rain: averages 42.2 inches of rain a year
Snow: averages 15.5 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 St. Louis is 7.2 (10=best), which means it is more comfortable than most places in Missouri.

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

45°F

Today's Weather - St. Louis, MO

71°F

Average Monthly High / Low (°F)

Hot, Freezing, Rainy, Snowy Days: Boulder / St. Louis

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 St. Louis with an average high temperature of 88.5°, which ranks it as about average compared to other places in Missouri. In St. Louis, there are 3 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for St. Louis are May, September and June.

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 St. Louis with an average of 22.8°. This is warmer than most places in Missouri.

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 St. Louis, there are 36.0 days annually when the high temperature is over 90°, which is hotter than most places in Missouri.

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 St. Louis, there are 91.1 days annually when the nighttime low temperature falls below freezing, which is warmer than most places in Missouri.

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 St. Louis, there are 1.5 days annually when the nighttime low temperature falls below zero°, which is warmer than most places in Missouri.

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 wettest month in St. Louis with 4.8 inches of rain, and the driest month is February with 2.3 inches. The wettest season is Summer with 29% of yearly precipitation and 18% occurs in Spring, which is the driest season. The annual rainfall of 42.2 inches in St. Louis means that it is drier than most places in Missouri.

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.

May is the rainiest month in St. Louis with 11.3 days of rain, and September is the driest month with only 7.0 rainy days. There are 105.3 rainy days annually in St. Louis, which is rainier than most places in Missouri. The rainiest season is Summer when it rains 30% of the time and the driest is Spring with only a 23% 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 15.5 inches in St. Louis means that it is snowier than most places in Missouri.

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

January is the snowiest month in St. Louis with 4.9 inches of snow, and 5 months of the year have significant snowfall.