Boise County Weather in May
Average highs run from 62°F on May 1 to 70°F on May 31, and lows from 31°F to 38°F. Normal precipitation for the month is 2.11 in over about 8 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
- 66°F
- Average low
- 35°F
- Precipitation
- 2.11 in
- Snowfall
- 0.8 in
- Record high
- 100°FMay 31, 2025
- Record low
- 22°FMay 5, 1982
- Chance of a freeze
- 100%
- Daylight
- 14 h 12 min to 15 h 14 min
- Cloud cover
- 66%
- Humidity
- 67%
- Dew point
- 35°F
- Wind
- 4.5 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 | 62°F | 31°F | 88°F 1985 | 27°F 1954 | 30% | 5% |
| May 2 | 62°F | 31°F | 91°F 1947 | 23°F 1988 | 30% | 4% |
| May 3 | 62°F | 31°F | 90°F 1966 | 28°F 1959 | 30% | 4% |
| May 4 | 63°F | 31°F | 93°F 1966 | 26°F 1982 | 29% | 4% |
| May 5 | 63°F | 32°F | 94°F 1966 | 22°F 1982 | 29% | 4% |
| May 6 | 63°F | 32°F | 95°F 1947 | 27°F 1964 | 29% | 3% |
| May 7 | 64°F | 32°F | 93°F 1987 | 26°F 1981 | 29% | 3% |
| May 8 | 64°F | 33°F | 94°F 1987 | 28°F 2002 | 29% | 3% |
| May 9 | 65°F | 33°F | 88°F 2025 | 29°F 1999 | 28% | 3% |
| May 10 | 65°F | 33°F | 92°F 1940 | 27°F 1999 | 28% | 3% |
| May 11 | 65°F | 33°F | 93°F 1941 | 27°F 1943 | 28% | 3% |
| May 12 | 66°F | 34°F | 96°F 2026 | 24°F 1985 | 28% | 2% |
| May 13 | 66°F | 34°F | 95°F 2013 | 26°F 1974 | 27% | 2% |
| May 14 | 66°F | 34°F | 91°F 1975 | 28°F 1986 | 27% | 2% |
| May 15 | 66°F | 34°F | 93°F 2006 | 28°F 1990 | 27% | 2% |
| May 16 | 67°F | 35°F | 94°F 2006 | 28°F 1974 | 27% | 2% |
| May 17 | 67°F | 35°F | 94°F 2008 | 30°F 1942 | 27% | 2% |
| May 18 | 67°F | 35°F | 95°F 2009 | 30°F 1971 | 27% | 2% |
| May 19 | 68°F | 35°F | 90°F 1954 | 28°F 1960 | 27% | 2% |
| May 20 | 68°F | 36°F | 94°F 1958 | 33°F 1971 | 26% | 2% |
| May 21 | 68°F | 36°F | 91°F 2023 | 33°F 1960 | 26% | 2% |
| May 22 | 68°F | 36°F | 93°F 1988 | 28°F 1960 | 26% | 2% |
| May 23 | 69°F | 36°F | 95°F 2001 | 32°F 1944 | 26% | 2% |
| May 24 | 69°F | 37°F | 97°F 2001 | 33°F 1975 | 26% | 2% |
| May 25 | 69°F | 37°F | 96°F 1961 | 30°F 1975 | 26% | 2% |
| May 26 | 69°F | 37°F | 98°F 1966 | 33°F 1973 | 26% | 2% |
| May 27 | 69°F | 37°F | 94°F 1983 | 32°F 1991 | 26% | 1% |
| May 28 | 70°F | 37°F | 99°F 2003 | 34°F 1982 | 26% | 1% |
| May 29 | 70°F | 38°F | 95°F 1986 | 32°F 1976 | 25% | 1% |
| May 30 | 70°F | 38°F | 98°F 1986 | 33°F 1979 | 25% | 1% |
| May 31 | 70°F | 38°F | 100°F 2025 | 32°F 1955 | 25% | 1% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (MDT).
- May 1
- sunrise 6:34 AM, sunset 8:46 PM
- May 31
- sunrise 6:04 AM, sunset 9:18 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00104442 (Idaho City), public domain. Records: NOAA GHCN-Daily, station USW00024131, 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 2026-09-25. Sun and moon: computed with the NOAA solar equations and Meeus.