Climate Insights for Boulder

The climate in Boulder is cool. The average annual temperature is 4°C and approximately 567mm of precipitation falls per year. Giugno is the wettest month, receiving around 93mm of rainfall. Boulder is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: Luglio, Agosto, Giugno. The coldest months are Dicembre, Gennaio, Febbraio, when temperatures can drop to -12°C. Snowfall occurs from January to December, with around 156cm accumulating over the season.

Boulder has a wide annual temperature range, spanning 39°C from the coldest to warmest months. The warmest month is Luglio, when average highs reach 27°C and the mean temperature sits around 18°C. The coldest month is Dicembre, when overnight lows fall to -12°C and the daily average is -8°C. On average, daily temperatures fluctuate by about 12°C between overnight lows and afternoon highs. The sharpest temperature change occurs between September and October, with a 8°C shift in average temperatures.

Boulder is a relatively dry area, receiving approximately 567mm of precipitation annually, which averages out to around 47mm per month. The wettest month is June, averaging 93mm of rainfall. May and April also tend to see above-average precipitation. The driest month is January, with just 23mm. That's 70mm less than June, the wettest month. Precipitation varies noticeably between seasons, with the first half (January to June) of the year generally seeing more rainfall. Snowfall is a regular feature from January to December, with around 156cm accumulating over the season. February typically sees the most snow at around 26cm.

Boulder is mildly breezy, with an average annual wind speed of 13km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is June, averaging 14km/h, though still comfortable for most outdoor activities. The calmest conditions occur in January, with average winds dropping to 11km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 3km/h between the calmest and windiest months.

It is currently spring in Boulder, which began on March 20, 2026. Boulder is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in Luglio at around 27°C, while the coldest stretch bottoms out in Dicembre near -12°C. Summer is next, beginning on June 21, 2026 — 93 days from now.

The best time to visit Boulder is during Luglio and Agosto, when the weather is most comfortable for travellers. During these months, average temperatures hover around 18°C with modest rainfall averaging 41mm per month. By contrast, Dicembre can be quite cold with temperatures dropping to -12°C. A light rain jacket is recommended, though showers are generally brief and shouldn't disrupt your plans.

The table below shows monthly climate averages for Boulder based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.