Boulder (CO) Weather and Climate: A Comprehensive Guide
Boulder experiences great temperature shifts.
The city's weather can transition from very warm days
to cold weather.
It receives a moderate amount of precipitation.
Let’s explore the climate details in depth to provide you with a complete overview.
Average maximum day and minimum night temperature
The climate in Boulder is known for significant temperature differences throughout the year, making the weather dynamic. On average, daytime temperatures range from a very warm 31°C in July to a chilly 7°C in December.
Nighttime temperatures can drop, with average lows reaching -7°C in December. Check out our detailed temperature page for more information.Temperature ranges by month
Precipitation and rainy days
Generally, Boulder receives mid-range precipitation levels, with 513 mm annually. The seasons in Boulder, bring significant changes in precipitation. The wettest month, May, receives moderate rainfall, with an average of 80 mm of precipitation. This rainfall is distributed across 12 rainy days. In contrast, the driest month, January, experiences much less snowfall, totaling 16 mm over 5 snowy days. These distinct seasonal differences provide diverse experiences throughout the year. For more details, please visit our Boulder Precipitation page.The mean monthly precipitation over the year, including rain, hail and snow
The average number of days each month with precipitation
Sunshine over the year
In Boulder, summer days are longer and more sunny, with daily sunshine hours peaking at 10.8 hours in July. As the darker season arrives, the brightness of the sun becomes less. November sees a soft sun for only 6.5 hours per average day. Visit our detailed sunshine hours page for more information.Monthly hours of sunshine
Daily hours of sunshine
Daily percentage of sunshine
Average humidity
The relative humidity is moderate throughout the year in Boulder.
The city experiences its highest humidity in December, reaching 56%. In July, the humidity drops to its lowest level at 46%. Explore our detailed page on humidity levels for further details.
Relative humidity over the year
broken clouds and no rain broken clouds and no rain partly cloudy and no rainForecast for Boulder (CO)
4 m/s
3 m/s
3 m/s
The best time of year to visit Boulder in the United States of America
During the months of May and September you are most likely to experience good weather with pleasant average temperatures that fall between 20°C and 26°C.Other facts from our historical weather data:
The hottest season / summer takes place in June, July, August and September.
Yes, the months of January and November are very dry.
July has an average maximum temperature of 31°C and is the warmest month of the year.
The coldest month is December with an average maximum temperature of 7°C.
May tops the wettest month list with 80 mm of rainfall.
January is the driest month with 16 mm of precipitation.
July is the sunniest month with an average of 323 hours of sunshine.
No idea where to travel to this year? We have a tool that recommends destinations based on your ideal conditions. Find out where to go with our weather planner.
