Boulder weather by month
Average highs run from 47°F in January to 88°F in July, and January nights average 22°F. It gets 21 inches of rain and melted snow a year and 93 inches of snow. Expect about 33 days a year at 90°F or hotter. Nights drop below freezing about 138 times a year. The most comfortable months are May to June and August to September.
Best time to visit Boulder
For comfortable weather, go in May to June and August to September. In those months the average high stays between 62°F and 86°F, nights average 42°F or warmer, and rain stays under 4.5 inches for the month.
Month by month
| Month | High | Low | Precip. | Snow | Wet days | Days 90°F+ | Nights below 32°F | Feels |
|---|---|---|---|---|---|---|---|---|
| January | 47°F | 22°F | 0.8 in | 11.3 in | 3 | 0 | 27 | cold |
| February | 48°F | 22°F | 1.0 in | 15.0 in | 4 | 0 | 23 | cool |
| March | 57°F | 29°F | 2.0 in | 15.7 in | 4 | 0 | 20 | cool |
| April | 63°F | 35°F | 3.1 in | 14.7 in | 6 | 0 | 11 | mild days, chilly nights |
| May | 71°F | 43°F | 3.2 in | 2.0 in | 7 | 1 | 2 | mild |
| June | 83°F | 51°F | 2.0 in | 0.0 in | 5 | 6 | 0 | warm |
| July | 88°F | 57°F | 1.8 in | 0.0 in | 4 | 14 | 0 | hot |
| August | 86°F | 56°F | 1.7 in | 0.0 in | 4 | 10 | 0 | warm |
| September | 79°F | 48°F | 2.1 in | 1.0 in | 4 | 3 | 1 | warm |
| October | 66°F | 37°F | 1.6 in | 7.0 in | 4 | 0 | 8 | mild days, chilly nights |
| November | 55°F | 28°F | 1.2 in | 13.1 in | 3 | 0 | 20 | cool |
| December | 46°F | 21°F | 0.8 in | 13.0 in | 3 | 0 | 27 | cold |
| Year | 66°F avg | 37°F avg | 21.2 in | 92.8 in | 49 | 33 | 138 |
"Wet days" are days with at least 0.1 inch of precipitation. "Feels" is a plain-language label for the average high. Normals for 1991-2020 from NOAA NCEI, station Boulder, CO (USC00050848), 2.5 miles from the city center. Averages describe typical conditions, not a forecast.
Sunrise, sunset and daylight in Boulder
The shortest day is December 21, with 9h 19m of daylight; the longest is June 21, with 15h 01m. The earliest sunset comes around December 2 (4:35 pm) and the latest around June 20 (8:33 pm). The sun sets after 8 pm on 100 days a year.
| On the 15th of | Sunrise | Sunset | Daylight |
|---|---|---|---|
| January | 7:21 am | 5:00 pm | 9h 39m |
| February | 6:54 am | 5:36 pm | 10h 43m |
| March | 7:12 am | 7:07 pm | 11h 55m |
| April | 6:23 am | 7:39 pm | 13h 16m |
| May | 5:45 am | 8:09 pm | 14h 24m |
| June | 5:31 am | 8:31 pm | 15h 00m |
| July | 5:45 am | 8:28 pm | 14h 43m |
| August | 6:13 am | 7:57 pm | 13h 44m |
| September | 6:42 am | 7:09 pm | 12h 27m |
| October | 7:11 am | 6:21 pm | 11h 09m |
| November | 6:46 am | 4:44 pm | 9h 58m |
| December | 7:16 am | 4:36 pm | 9h 20m |
Calculated for 2026 at the center of Boulder with NOAA's solar equations, in local clock time (Mountain Time, including daylight saving time where it applies). Times shift by a minute or two from year to year.
Is Boulder getting warmer?
The last 10 years averaged 1.9°F warmer than the 20th century. See the climate stripes for Boulder.Frequently asked questions
What is the warmest month in Boulder?
July is the warmest month, with an average high of 88°F and an average low of 57°F (NOAA 1991-2020 normals).
What is the coldest month in Boulder?
December is the coldest, with average lows of 21°F and highs of 46°F.
What is the rainiest month in Boulder?
May gets the most precipitation, 3.2 inches on average. December is the driest at 0.8 inches.
Does it snow in Boulder?
Yes. Boulder averages 93 inches of snow a year.
When is the best time to visit Boulder?
For comfortable weather, May to June and August to September. Those months average highs between 62 and 86°F with lows of 42°F or more and modest rain.
Thinking of moving to Boulder?
See what homes, rent and everyday prices cost, who lives there and how it compares with nearby cities on the full Boulder profile.
Compare the weather: Boulder vs Longmont, Boulder vs Broomfield, Boulder vs Arvada, Boulder vs Westminster.