2025 Compare Climate & Weather:
Boulder, CO vs Waltham, MA

Highlights

On average, there are 197 sunny days per year in Waltham. Boulder averages 245 sunny days per year. The US average is 205 sunny days.

Waltham, Massachusetts gets 47.7 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.

Waltham averages 50.2 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

Waltham, Massachusetts
Summer High: the July high is around 82.9 degrees
Winter Low: the January low is 17.1
Rain: averages 47.7 inches of rain a year
Snow: averages 50.2 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 Waltham is 6.9 (10=best), which means it is about average compared to other places in Massachusetts.

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

83°F

Today's Weather - Waltham, MA

67°F

Average Monthly High / Low (°F)

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

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 Waltham with an average high temperature of 82.9°, which ranks it as warmer than most places in Massachusetts. In Waltham, there are 4 comfortable months with high temperatures in the range of 70-85°. The most pleasant months of the year for Waltham are June, August and September.

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 Waltham with an average of 17.1°. This is about average compared to other places in Massachusetts.

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 Waltham, there are 9.9 days annually when the high temperature is over 90°, which is hotter than most places in Massachusetts.

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 Waltham, there are 129.8 days annually when the nighttime low temperature falls below freezing, which is about average compared to other places in Massachusetts.

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 Waltham, there are 3.1 days annually when the nighttime low temperature falls below zero°, which is colder than most places in Massachusetts.

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.


March is the wettest month in Waltham with 4.4 inches of rain, and the driest month is February with 3.3 inches. The wettest season is Summer with 26% of yearly precipitation and 23% occurs in Spring, which is the driest season. The annual rainfall of 47.7 inches in Waltham means that it is about average compared to other places in Massachusetts.

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 Waltham with 12.8 days of rain, and September is the driest month with only 9.2 rainy days. There are 130.6 rainy days annually in Waltham, which is rainier than most places in Massachusetts. The rainiest season is Summer when it rains 28% of the time and the driest is Winter with only a 24% 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 50.2 inches in Waltham means that it is snowier than most places in Massachusetts.

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 Waltham with 14.9 inches of snow, and 6 months of the year have significant snowfall.