Boulder, CO Weather
Boulder hourly forecast: next 24 hours
Today's high of 86°F (30°C) is about 3°F (2°C) above the typical August high of 83°F (28°C).
Current conditions in detail
Boulder weather tomorrow (Thursday, August 27)
Tomorrow in Boulder looks sunny, with a high of 87° and an overnight low of 56°. There is a 57% chance of rain - plan accordingly. Winds top out near 13 mph, and the UV index reaches 9 (very high).
Boulder 14-day forecast
About the weather in Boulder
Seasons are the whole story in Boulder. The gap between an average July and an average January is 25°C - hot, humid summers and generally mild winters - which in practice means 85°F (30°C) afternoons at one end of the calendar and 38°F (3°C) at the other.
Boulder weather: quick facts
- Hottest month: July - highs near 85°F (30°C)
- Coldest month: January - highs near 38°F (3°C)
- Decade extremes (2015-2024): 98°F (37°C) high · -24°F (-31°C) low
- Wettest month: May (15 rainy days) · Sunniest: July (13.1 h sun/day)
- Climate type: humid subtropical
- Annual swing: 25°C between the average warmest and coolest month · day to night: 14°C
- Snow: about 34 days a year
- Months with freezing average lows: 6
- Average humidity: 56%
Temperatures through the year
January sits at the other end of the year: 38°F (3°C) by day, 17°F (-8°C) at night. Warmth peaks in July: highs of 85°F (30°C), lows of 59°F (15°C). Across the gridded 2015-2024 daily record, the highest daily maximum for this location was 98°F (37°C) and the lowest daily minimum -24°F (-31°C). May is the wettest month at 4.6 inches (116 mm) over 15 days; December is the driest.
Rain, sun and snow
Between the average July and the average January lie 25°C, a wider spread than roughly 84% of the cities we track. Snow falls on roughly 34 days a year, mostly October through May.
Season by season
Spring (March through May)
Spring runs cool rather than cold here - highs near 57°F (14°C), nights near 32°F (0°C), and rain falls on around 33 of the 90 days, plus about 13 snowy days. Daylight is generous - around 10.9 hours of sun a day.
Summer (June through August)
Summer brings hot afternoons here - highs near 83°F (28°C), nights near 57°F (14°C), and expect showers on roughly 25 days across the season. Daylight is generous - around 12.8 hours of sun a day.
Fall (September through November)
Fall is crisp but comfortable here - highs near 64°F (18°C), nights near 39°F (4°C), and expect showers on roughly 18 days across the season, plus about 7 snowy days.
Winter (December through February)
Winter in Boulder is brisk and 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 about 14 snowy days.
Average temperatures in Boulder by month
| Month | High | Low | Rain days | Precipitation | Sunshine | Humidity |
|---|---|---|---|---|---|---|
| January | 38° | 17° | 6 | 1.0 in | 7.9 h/day | 61% |
| February | 39° | 15° | 7 | 1.4 in | 9.1 h/day | 61% |
| March | 49° | 24° | 8 | 2.1 in | 10.1 h/day | 61% |
| April | 57° | 31° | 10 | 2.3 in | 10.9 h/day | 58% |
| May | 65° | 41° | 15 | 4.6 in | 11.7 h/day | 64% |
| June | 80° | 54° | 8 | 1.9 in | 13.0 h/day | 52% |
| July | 85° | 59° | 9 | 1.5 in | 13.1 h/day | 50% |
| August | 83° | 58° | 8 | 1.4 in | 12.3 h/day | 50% |
| September | 78° | 52° | 6 | 1.0 in | 11.2 h/day | 47% |
| October | 63° | 38° | 6 | 1.3 in | 9.7 h/day | 53% |
| November | 49° | 27° | 6 | 1.3 in | 8.5 h/day | 57% |
| December | 42° | 20° | 5 | 0.9 in | 7.8 h/day | 56% |