Boulder, CO Climate

Climate Insight: Boulder, CO

The NOAA 1991–2020 climate normals describe Boulder, Colorado as a location with an annual average temperature of 35°F, ranging from a mean daily high of 46°F to a mean daily low of 25°F. July is typically the warmest month of the year, while February is the coldest. These thirty-year averages, computed from 2 weather stations, smooth out year-to-year variability and give a baseline expectation for typical conditions in any given month.

Precipitation patterns matter as much as temperature for anyone planning to live, garden, or travel here. Boulder receives roughly 33.9 inches of precipitation each year, with seasonal snowfall possible. Growing-season length varies with elevation and microclimate, with the last spring freeze near June 21 and the first fall freeze near September 2. For energy use, 10,824 heating degree days and 0 cooling degree days tell the story of how often furnaces and air conditioners run during a normal year.

On PlainClimate's composite comfort index, Boulder scores 57/100 (Moderate), a blended measure that weighs temperature mildness, precipitation moderation, and extreme-weather frequency against one another. Use the monthly tables above to plan around specific windows — shoulder seasons for mild highs and lows, peak summer for July-driven heat, or deep winter for February-driven cold. All figures here are thirty-year averages: any single year may run warmer, wetter, drier, or cooler than the normal, so treat them as planning guidance rather than forecasts.