Boulder County Weather in May
Average highs run from 66°F on May 1 to 77°F on May 31, and lows from 38°F to 47°F. Normal precipitation for the month is 3.21 in over about 13 wet days.
May day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
May at a glance
- Average high
- 71°F
- Average low
- 43°F
- Precipitation
- 3.21 in
- Snowfall
- 2.0 in
- Record high
- 95°FMay 28, 2000
- Record low
- 17°FMay 2, 2013
- Chance of a freeze
- 73%
- Days of 90°F or more
- 0.5
- Daylight
- 13 h 56 min to 14 h 49 min
- Cloud cover
- 70%
- Humidity
- 59%
- Dew point
- 28°F
- Wind
- 6.7 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.
| Date | Normal high | Normal low | Record high | Record low | Chance wet | Chance of snow |
|---|---|---|---|---|---|---|
| May 1 | 66°F | 38°F | 86°F 1943 | 23°F 1909 | 37% | 9% |
| May 2 | 66°F | 38°F | 86°F 1981 | 17°F 2013 | 37% | 9% |
| May 3 | 67°F | 39°F | 86°F 1947 | 20°F 1907 | 38% | 8% |
| May 4 | 67°F | 39°F | 88°F 2000 | 28°F 1935 | 38% | 8% |
| May 5 | 67°F | 39°F | 89°F 2000 | 29°F 1908 | 38% | 7% |
| May 6 | 67°F | 40°F | 87°F 1963 | 22°F 1917 | 38% | 7% |
| May 7 | 68°F | 40°F | 87°F 1963 | 28°F 2010 | 39% | 7% |
| May 8 | 68°F | 40°F | 86°F 1895 | 30°F 2010 | 39% | 6% |
| May 9 | 69°F | 41°F | 88°F 1916 | 25°F 2002 | 39% | 6% |
| May 10 | 69°F | 41°F | 88°F 1916 | 27°F 1946 | 39% | 5% |
| May 11 | 69°F | 41°F | 88°F 1916 | 21°F 1946 | 39% | 5% |
| May 12 | 70°F | 42°F | 88°F 1962 | 24°F 1953 | 40% | 5% |
| May 13 | 70°F | 42°F | 89°F 1988 | 27°F 1953 | 40% | 4% |
| May 14 | 70°F | 42°F | 88°F 1996 | 29°F 1907 | 40% | 4% |
| May 15 | 71°F | 43°F | 93°F 1978 | 29°F 1916 | 40% | 4% |
| May 16 | 71°F | 43°F | 93°F 1996 | 30°F 1923 | 40% | 4% |
| May 17 | 72°F | 43°F | 92°F 1964 | 28°F 1942 | 40% | 3% |
| May 18 | 72°F | 43°F | 90°F 1996 | 29°F 1915 | 40% | 3% |
| May 19 | 72°F | 44°F | 90°F 2006 | 26°F 1915 | 40% | 3% |
| May 20 | 73°F | 44°F | 93°F 1954 | 27°F 1931 | 40% | 3% |
| May 21 | 73°F | 44°F | 90°F 2006 | 26°F 2001 | 40% | 3% |
| May 22 | 74°F | 45°F | 89°F 2012 | 30°F 2022 | 40% | 2% |
| May 23 | 74°F | 45°F | 90°F 1967 | 34°F 1930 | 40% | 2% |
| May 24 | 74°F | 45°F | 90°F 1967 | 32°F 1995 | 40% | 2% |
| May 25 | 75°F | 46°F | 87°F 1967 | 32°F 1950 | 40% | 2% |
| May 26 | 75°F | 46°F | 91°F 1969 | 32°F 1950 | 40% | 2% |
| May 27 | 76°F | 46°F | 92°F 2006 | 33°F 1950 | 40% | 1% |
| May 28 | 76°F | 46°F | 95°F 2000 | 30°F 1908 | 40% | 1% |
| May 29 | 76°F | 47°F | 95°F 2000 | 30°F 1947 | 40% | 1% |
| May 30 | 77°F | 47°F | 91°F 1984 | 34°F 1973 | 39% | 1% |
| May 31 | 77°F | 47°F | 89°F 2002 | 34°F 1917 | 39% | 1% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (MDT).
- May 1
- sunrise 6:01 AM, sunset 7:57 PM
- May 31
- sunrise 5:35 AM, sunset 8:24 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00050848 (Boulder), public domain. Records: NOAA GHCN-Daily, station USC00050848, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.