Air Quality Alert
The Colorado Department of Public Health and Environment has
issued the following...
WHAT...Action Day for Multiple Pollutants.
WHERE...Douglas, Jefferson, Denver, western Arapahoe, western
Adams, Broomfield, Boulder, Larimer, and Weld Counties
WHEN...400 PM Wednesday August 0…
Air Quality Alert
The Colorado Department of Public Health and Environment has
issued the following...
WHAT...Action Day for Multiple Pollutants.
WHERE...Douglas, Jefferson, Denver, western Arapahoe, western
Adams, Broomfield, Boulder, Larimer, and Weld Counties
WHEN...400 PM Wednesday August 0…
Tomorrow in Boulder looks
sunny, with a high of 97°
and an overnight low of 61°.
Rain is unlikely (1% chance).
Winds top out near 10 mph,
and the UV index reaches 10 (very high).
Located in Colorado, United States, Boulder experiences a humid subtropical climate with hot, humid summers and generally mild winters. Afternoon temperatures peak near 85°F (30°C) in July and dip to about 38°F (3°C) in January, with around 20.6 inches (524 mm) of precipitation falling across the year.
Boulder weather: quick facts
Hottest month: July - highs near 85°F (30°C)
Coldest month: January - highs near 38°F (3°C)
Record high: 98°F (37°C) · Record low: -24°F (-31°C) (2015–2024)
Wettest month: May (15 rainy days) · Sunniest: July (13.1 h sun/day)
Climate type:humid subtropical - hot, humid summers and generally mild winters
Snow: about 34 days a year
Temperatures through the year
The warmest stretch of the year centers on July. Highs average 85°F (30°C) and overnight lows stay near 59°F (15°C). The coolest month is January, with typical highs of 38°F (3°C) and lows around 17°F (-8°C). Based on 2015–2024 weather data, temperatures have reached as high as 98°F (37°C) and dropped as low as -24°F (-31°C).
Rain, sun and snow
May is usually the wettest month. It brings about 4.6 inches (116 mm) of rain over 15 days, while December is the driest. July brings the most sunshine, averaging 13.1 hours of sun a day. Snow falls on about 34 days in a typical year, mostly from October through May.
Season by season
Spring (March through May)
Spring in Boulder is mild, with daytime highs averaging 57°F (14°C) and nights around 32°F (0°C); expect showers on roughly 33 days across the season, plus around 13 snowy days.
Summer (June through August)
Summer in Boulder is hot, with daytime highs averaging 83°F (28°C) and nights around 57°F (14°C); expect showers on roughly 25 days across the season.
Fall (September through November)
Fall in Boulder stays on the cool side of mild, with daytime highs averaging 64°F (18°C) and nights around 39°F (4°C); expect showers on roughly 18 days across the season, plus around 7 snowy days.
Winter (December through February)
Winter in Boulder runs cold, with daytime highs averaging 40°F (4°C) and nights around 18°F (-8°C); expect showers on roughly 18 days across the season, plus around 14 snowy days.
Average temperatures in Boulder by month
Monthly averages for Boulder based on 2015–2024 weather data.
July is the hottest month in Boulder, with average highs of 85°F (30°C) and overnight lows near 59°F (15°C). In the past decade the temperature has peaked at 98°F (37°C).
What is the coldest month in Boulder?
January is the coldest month, with highs averaging 38°F (3°C) and lows around 17°F (-8°C). The lowest reading in recent years was -24°F (-31°C).
What is the rainiest month in Boulder?
May is typically the wettest month, averaging 4.6 inches (116 mm) of precipitation across about 15 days. December is usually the driest.
Does it snow in Boulder?
Yes. Boulder averages about 34 days of snowfall a year, concentrated October through May.
What is the best time to visit Boulder?
The best time to visit Boulder is generally August to October and June, when warm days, manageable rainfall and plenty of daylight line up. Daytime temperatures in that window typically sit near 76°F (24°C).
How sunny is Boulder?
Boulder averages 10.4 hours of sunshine per day across the year. July is the sunniest month at about 13.1 hours of sun a day.
Is Boulder humid?
Relative humidity in Boulder averages about 56% over the year, which feels moderate. The most comfortable months tend to fall in the drier part of the year.