Great Falls Weather in May
Average highs run from 78°F on May 1 to 84°F on May 31, and lows from 53°F to 61°F. Normal precipitation for the month is 3.07 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
- 81°F
- Average low
- 57°F
- Precipitation
- 3.07 in
- Record high
- 100°FMay 23, 1941
- Record low
- 34°FMay 9, 1989
- Chance of a freeze
- 2%
- Days of 90°F or more
- 3.6
- Daylight
- 13 h 35 min to 14 h 19 min
- Cloud cover
- 55%
- Humidity
- 73%
- Dew point
- 60°F
- Wind
- 4.0 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 | 78°F | 53°F | 92°F 1962 | 38°F 1908 | 28% | 0% |
| May 2 | 78°F | 53°F | 91°F 1901 | 36°F 1963 | 28% | 0% |
| May 3 | 79°F | 53°F | 93°F 1901 | 39°F 1940 | 28% | 0% |
| May 4 | 79°F | 54°F | 93°F 1913 | 37°F 1971 | 28% | 0% |
| May 5 | 79°F | 54°F | 96°F 1936 | 38°F 1940 | 28% | 0% |
| May 6 | 79°F | 54°F | 92°F 1952 | 40°F 1945 | 28% | 0% |
| May 7 | 79°F | 54°F | 95°F 1940 | 40°F 1989 | 28% | 0% |
| May 8 | 80°F | 55°F | 96°F 1940 | 41°F 1944 | 28% | 0% |
| May 9 | 80°F | 55°F | 96°F 1936 | 34°F 1989 | 28% | 0% |
| May 10 | 80°F | 55°F | 95°F 1936 | 35°F 1906 | 28% | 0% |
| May 11 | 80°F | 56°F | 98°F 1916 | 39°F 1966 | 28% | 0% |
| May 12 | 80°F | 56°F | 95°F 1911 | 38°F 2020 | 28% | 0% |
| May 13 | 81°F | 56°F | 92°F 1914 | 40°F 1960 | 28% | 0% |
| May 14 | 81°F | 56°F | 95°F 1933 | 41°F 1917 | 28% | 0% |
| May 15 | 81°F | 57°F | 95°F 1933 | 41°F 1910 | 28% | 0% |
| May 16 | 81°F | 57°F | 95°F 1941 | 43°F 1978 | 28% | 0% |
| May 17 | 81°F | 57°F | 94°F 1911 | 42°F 1934 | 28% | 0% |
| May 18 | 82°F | 57°F | 96°F 1911 | 40°F 1973 | 28% | 0% |
| May 19 | 82°F | 58°F | 95°F 1931 | 42°F 1976 | 28% | 0% |
| May 20 | 82°F | 58°F | 97°F 1933 | 43°F 2002 | 28% | 0% |
| May 21 | 82°F | 58°F | 98°F 1941 | 43°F 1954 | 28% | 0% |
| May 22 | 82°F | 59°F | 99°F 1941 | 42°F 2002 | 29% | 0% |
| May 23 | 83°F | 59°F | 100°F 1941 | 45°F 2002 | 29% | 0% |
| May 24 | 83°F | 59°F | 98°F 1903 | 41°F 1931 | 29% | 0% |
| May 25 | 83°F | 59°F | 95°F 1915 | 45°F 1935 | 29% | 0% |
| May 26 | 83°F | 60°F | 99°F 1918 | 42°F 1979 | 29% | 0% |
| May 27 | 83°F | 60°F | 100°F 1926 | 38°F 1961 | 29% | 0% |
| May 28 | 84°F | 60°F | 99°F 1914 | 43°F 1907 | 30% | 0% |
| May 29 | 84°F | 61°F | 99°F 1941 | 47°F 1922 | 30% | 0% |
| May 30 | 84°F | 61°F | 97°F 1953 | 48°F 1913 | 30% | 0% |
| May 31 | 84°F | 61°F | 97°F 1953 | 42°F 1984 | 30% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (EDT).
- May 1
- sunrise 6:33 AM, sunset 8:08 PM
- May 31
- sunrise 6:12 AM, sunset 8:31 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00389327 (Winnsboro), public domain. Records: NOAA GHCN-Daily, station USC00389350, 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.