Boulder, Colorado 

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Climate in Boulder, Colorado

Boulder, CO has a mild climate with warm summers and cold winters. During the summer months, temperatures can reach up to the 90s Fahrenheit (32-37 °C), while during winter temperatures usually stay between 20-30 °F (-7 to -1 °C). The climate is relatively dry in Boulder with an average of 12 inches of precipitation per year. The city also experiences four distinct seasons which bring a variety of weather conditions such as snowfall in the winter and occasional thunderstorms in the summer. In addition to being one of the sunniest cities in Colorado, Boulder receives a great deal of sunshine year round, making it the perfect place for outdoor activities.

Boulder, Colorado gets 18 inches of rain, on average, per year. The US average is 38 inches of rain per year.

Boulder averages 71 inches of snow per year. The US average is 28 inches of snow per year.

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

Boulder gets some kind of precipitation, on average, 88 days per year. Precipitation is rain, snow, sleet, or hail that falls to the ground. In order for precipitation to be counted you have to get at least .01 inches on the ground to measure.

Weather Highlights

Summer High: the July high is around 88 degrees
Winter Low: the January low is 19
Rain: averages 18 inches of rain a year
Snow: averages 71 inches of snow a year


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

8.6 / 5.6

Summer   /   Winter
September, June and August are the most pleasant months in Boulder, while December and January are the least comfortable months.

Climate Averages
  Boulder, ColoradoUnited States
  18.1 in.38.1 in.
  71.1 in.27.8 in.
  88.0 days106.2 days
  245 days205 days
  5328 ft.2443 ft.


Many people confuse weather and climate but they are different. Weather is the conditions of the atmosphere over a short period of time, and climate is how the atmosphere is over long periods of time.

Weather is how the atmosphere is behaving and its effects upon life and human activities. Weather can change from minute-to-minute. Most people think of weather in terms of temperature, humidity, precipitation, cloudiness, brightness, visibility, wind, and atmospheric pressure.

Climate is the description of the long-term pattern of weather in a place. Climate can mean the average weather for a particular region and time period taken over 30 years. Climate is the average of weather over time.

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.

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.

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

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

Humidity is low in Boulder, and some people might find the dryness to be uncomfortable. Days with noticeable humidity are rare throughout the year. A very dry climate can lead to cracked, itchy skin and dry eyes.

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 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 71.1 inches in Boulder means that it is snowier than most places in Colorado. March is the snowiest month in Boulder with 14.3 inches of snow, and 9 months of the year have significant snowfall.

  • Annual Rainfall (US Avg: 36.5")
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    Reviews for Boulder    55 Reviews
    Expensive and requires liking a unique culture - 6/29/2021
    Outside of the university, Boulder had a very distinctive "wealthy hippy" feel. A lot of alternative medicine and a matching ethos. This is changing some among my... Read More

    Start Your Review of Boulder

    I love it here! Such a beautiful and friendly city - 11/5/2020
    We moved here from Texas about 4 years ago and love it here! The amazing sense of community and high regard for the environment are two of the main reasons we love... Read More

    Snob says it's ok - 9/18/2020
    Most people do much worse than Boulder. I'm the most critical person I've ever met who is never happy or satisfied -- so that's a pretty huge compliment. ... Read More

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