Lewis and Clark County Weather in May
Average highs run from 57°F on May 1 to 66°F on May 31, and lows from 33°F to 43°F. Normal precipitation for the month is 2.99 in over about 10 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
- 62°F
- Average low
- 38°F
- Precipitation
- 2.99 in
- Snowfall
- 0.1 in
- Record high
- 89°FMay 27, 2003
- Record low
- 14°FMay 3, 1967
- Chance of a freeze
- 97%
- Daylight
- 14 h 28 min to 15 h 39 min
- Cloud cover
- 71%
- Humidity
- 71%
- Dew point
- 35°F
- Wind
- 5.4 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 | 57°F | 33°F | 78°F 1985 | 16°F 1967 | 28% | 2% |
| May 2 | 58°F | 34°F | 81°F 1985 | 15°F 1967 | 28% | 1% |
| May 3 | 58°F | 34°F | 78°F 2016 | 14°F 1967 | 29% | 1% |
| May 4 | 58°F | 34°F | 81°F 1966 | 19°F 1967 | 29% | 1% |
| May 5 | 59°F | 35°F | 85°F 2017 | 23°F 2010 | 29% | 1% |
| May 6 | 59°F | 35°F | 84°F 1966 | 20°F 1991 | 29% | 1% |
| May 7 | 60°F | 35°F | 86°F 1992 | 21°F 2010 | 29% | 1% |
| May 8 | 60°F | 36°F | 86°F 1992 | 22°F 1997 | 30% | 1% |
| May 9 | 60°F | 36°F | 77°F 2013 | 21°F 1990 | 30% | 1% |
| May 10 | 61°F | 36°F | 80°F 1994 | 20°F 1968 | 30% | 1% |
| May 11 | 61°F | 37°F | 79°F 2013 | 19°F 1983 | 30% | 1% |
| May 12 | 61°F | 37°F | 84°F 1993 | 19°F 2004 | 31% | 1% |
| May 13 | 62°F | 37°F | 86°F 2001 | 19°F 2004 | 31% | 1% |
| May 14 | 62°F | 38°F | 82°F 2001 | 28°F 2007 | 31% | 1% |
| May 15 | 62°F | 38°F | 82°F 1973 | 27°F 2017 | 32% | 1% |
| May 16 | 63°F | 39°F | 87°F 2006 | 18°F 1992 | 32% | 0% |
| May 17 | 63°F | 39°F | 87°F 2008 | 25°F 1977 | 33% | 0% |
| May 18 | 63°F | 39°F | 88°F 2006 | 29°F 2003 | 33% | 0% |
| May 19 | 64°F | 40°F | 81°F 1992 | 27°F 1997 | 33% | 0% |
| May 20 | 64°F | 40°F | 81°F 2002 | 22°F 2021 | 34% | 0% |
| May 21 | 64°F | 40°F | 87°F 1980 | 22°F 2021 | 34% | 0% |
| May 22 | 64°F | 41°F | 85°F 1980 | 29°F 2002 | 34% | 0% |
| May 23 | 65°F | 41°F | 83°F 1969 | 28°F 2002 | 35% | 0% |
| May 24 | 65°F | 41°F | 82°F 1988 | 30°F 1989 | 35% | 0% |
| May 25 | 65°F | 42°F | 84°F 2001 | 29°F 1967 | 35% | 0% |
| May 26 | 65°F | 42°F | 82°F 1999 | 31°F 2005 | 35% | 0% |
| May 27 | 66°F | 42°F | 89°F 2003 | 32°F 1982 | 35% | 0% |
| May 28 | 66°F | 42°F | 85°F 2003 | 31°F 1989 | 35% | 0% |
| May 29 | 66°F | 43°F | 85°F 1984 | 28°F 1989 | 36% | 0% |
| May 30 | 66°F | 43°F | 84°F 1984 | 30°F 2011 | 36% | 0% |
| May 31 | 66°F | 43°F | 86°F 1972 | 28°F 1982 | 36% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (MDT).
- May 1
- sunrise 6:13 AM, sunset 8:41 PM
- May 31
- sunrise 5:38 AM, sunset 9:17 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00247159 (Rogers Pass 9 Nne), public domain. Records: NOAA GHCN-Daily, station USC00247159, 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.