Climate Insights for Boulder

The climate in Boulder is cool. The average annual temperature is 8°C and approximately 652mm of precipitation falls per year. Maggio is the wettest month, receiving around 131mm 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 Gennaio, Febbraio, Dicembre, when temperatures can drop to -8°C. Snowfall occurs from January to December, with around 162cm accumulating over the season.

Boulder has a wide annual temperature range, spanning 36°C from the coldest to warmest months. The warmest month is Luglio, when average highs reach 28°C and the mean temperature sits around 20°C. The coldest month is Gennaio, when overnight lows fall to -8°C and the daily average is -4°C. On average, daily temperatures fluctuate by about 14°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 652mm of precipitation annually, which averages out to around 54mm per month. The wettest month is May, averaging 131mm of rainfall. June and July also tend to see above-average precipitation. The driest month is December, with just 23mm. That's 108mm less than May, the wettest month. Rainfall is heavily concentrated in certain months, creating a distinct wet and dry season. Visitors should plan around these patterns, as the difference between peak and low months is dramatic. Snowfall is a regular feature from January to December, with around 162cm accumulating over the season. March typically sees the most snow at around 30cm.

Boulder is mildly breezy, with an average annual wind speed of 14km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is April, averaging 15km/h, though still comfortable for most outdoor activities. The calmest conditions occur in August, with average winds dropping to 13km/h, making it an ideal period for wind-sensitive activities. Wind conditions are fairly consistent throughout the year, varying by only 2km/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 28°C, while the coldest stretch bottoms out in Gennaio near -8°C. Summer is next, beginning on June 21, 2026 — 93 days from now.

The best time to visit Boulder is during Giugno, Luglio, Agosto and Settembre, when the weather is most comfortable for travellers. During these months, average temperatures hover around 18°C with modest rainfall averaging 60mm per month. By contrast, Gennaio can be quite cold with temperatures dropping to -8°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.