May weather in Boulder, MT
The average temperature in Boulder in May is 49.4°F (35.3°F–63.6°F). Average precipitation: 1.86 inches.
May is a spring month in Boulder, and is warmer than the annual average of 42.6°F. Daily temperatures swing about 28.3°F between overnight low and afternoon high. Expect about 12 days with precipitation. Daylight averages about 14h 46m. For travel, May is cool.
Avg High
63.6°F
Avg Low
35.3°F
Precipitation
1.86 in
Daylight
14h 46m
May records in Boulder
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| May 1 | 78.1°F (1985) | 12.9°F (1954) | 0.49 in (1964) |
| May 2 | 79.0°F (1985) | 9.0°F (1967) | 0.49 in (1981) |
| May 3 | 81.0°F (1966) | 19.0°F (1965) | 0.44 in (2007) |
| May 4 | 82.9°F (1966) | 17.1°F (2024) | 0.70 in (1960) |
| May 5 | 84.0°F (1966) | 18.0°F (1996) | 1.33 in (2025) |
| May 6 | 84.0°F (1966) | 19.0°F (1996) | 0.47 in (1995) |
| May 7 | 84.0°F (1987) | 19.9°F (2012) | 1.30 in (1975) |
| May 8 | 82.9°F (1987) | 12.0°F (1996) | 0.23 in (1989) |
| May 9 | 82.0°F (1987) | 9.0°F (1996) | 0.36 in (1956) |
| May 10 | 80.1°F (1949) | 9.0°F (1996) | 1.67 in (2005) |
| May 11 | 84.0°F (1960) | 19.0°F (2012) | 0.78 in (1981) |
| May 12 | 84.0°F (1960) | 19.9°F (1985) | 0.44 in (1991) |
| May 13 | 82.9°F (2013) | 0.0°F (1995) | 0.40 in (2025) |
| May 14 | 84.0°F (2013) | 19.0°F (2004) | 0.97 in (2025) |
| May 15 | 84.0°F (2012) | 21.9°F (2004) | 1.00 in (1952) |
| May 16 | 86.0°F (1988) | 23.0°F (1974) | 0.60 in (2015) |
| May 17 | 84.9°F (1988) | 25.0°F (1986) | 0.66 in (1996) |
| May 18 | 86.0°F (1954) | 21.0°F (1965) | 0.75 in (1978) |
| May 19 | 89.1°F (1954) | 21.0°F (1997) | 0.42 in (1949) |
| May 20 | 84.9°F (1954) | 21.0°F (2003) | 0.74 in (1974) |
| May 21 | 84.0°F (1958) | 23.0°F (1989) | 0.82 in (2004) |
| May 22 | 89.1°F (1950) | 23.0°F (2009) | 0.73 in (2007) |
| May 23 | 84.0°F (1988) | 21.9°F (1966) | 0.97 in (2013) |
| May 24 | 84.0°F (1988) | 21.9°F (2021) | 1.70 in (1981) |
| May 25 | 84.9°F (2003) | 21.9°F (1950) | 1.32 in (1980) |
| May 26 | 84.9°F (1966) | 23.0°F (1975) | 0.43 in (1959) |
| May 27 | 88.0°F (1986) | 24.1°F (1973) | 0.52 in (2006) |
| May 28 | 89.1°F (1986) | 21.9°F (1955) | 0.67 in (2018) |
| May 29 | 87.1°F (1986) | 19.9°F (1954) | 1.00 in (1982) |
| May 30 | 89.1°F (1984) | 26.1°F (1977) | 1.17 in (1988) |
| May 31 | 89.1°F (1986) | 25.0°F (1982) | 0.57 in (1981) |