May is one of the warmer months of the year in Missoula, with average highs near 14.3°C and lows around 1.4°C (mean 7.9°C). It is a relatively wet time of year, averaging 76 mm of rainfall and 73% relative humidity across the period.
May is one of the warmer months of the year in Missoula. Across 45 years of records, the warmest May in Missoula was 2023 — when the month averaged 11.8°C — while the coldest was 1984 at 5.1°C. Typical May days reach 14.3°C with nights near 1.4°C. The long-term trend is warming, about 0.2°C per decade.
May is a relatively wet time of year in Missoula, averaging 76 mm of rainfall. The wettest May on record was 1981 with 123 mm, while the driest was 2001 at 29 mm.
Relative humidity in Missoula during May averages 73%. The most humid May was 1996 at 79%, and the least humid was 1992 at 61%.
May receives about 5.5 kWh/m²/day of solar energy in Missoula. The sunniest May was 2001 at 6.4 kWh/m²/day, and the cloudiest were 1990 and 1991 at 4.8.
Average wind speed in Missoula during May is 0.3 m/s. The windiest Mays were 2023, 2024 and 2025, among others at 0.3 m/s, while the calmest were 2018, 2019 and 2020, among others at 0.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 7.6°C | 8.0°C | 7.6°C | 8.0°C | 8.2°C | +0.6°C |
| Avg High | 14.3°C | 14.7°C | 14.0°C | 14.2°C | 14.5°C | +0.2°C |
| Avg Low | 1.0°C | 1.4°C | 1.2°C | 1.8°C | 1.8°C | +0.8°C |
| Avg Rain | 74 mm | 76 mm | 70 mm | 76 mm | 89 mm | +15 mm |
May temperatures in Missoula have risen by about 1.3°C between 1981–1985 and 2021–2025.
May has ranged from a record low of -8.7°C (2007) to a record high of 30.1°C (1986).
Rainfall in May is a relatively wet time of year, averaging 76 mm, with a wettest year of 123 mm.
A good time to visit Missoula
May is a good time to visit Missoula, with days averaging 14.3°C and nights around 1.4°C (mean 7.9°C, warmer than Missoula's yearly average) and moderate rainfall. July and August are marginally more temperate, but May still suits most travellers.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 16.9°C | 10.0°C | 3.1°C | 29.1°C | -4.0°C | 51 mm | 70% | 0.3 m/s | 6.1 |
| 2024 | 13.3°C | 7.0°C | 0.6°C | 25.2°C | -4.8°C | 90 mm | 73% | 0.3 m/s | 5.4 |
| 2023 🔥 | 18.2°C | 11.8°C | 5.3°C | 24.3°C | 1.9°C | 104 mm | 74% | 0.3 m/s | 5.9 |
| 2022 | 11.9°C | 6.0°C | 0.1°C | 19.4°C | -5.5°C | 63 mm | 75% | 0.3 m/s | 4.9 |
| 2021 | 12.9°C | 6.7°C | 0.5°C | 22.1°C | -4.8°C | 109 mm | 71% | 0.3 m/s | 5.6 |
| 2020 | 14.1°C | 7.6°C | 1.1°C | 27.1°C | -4.8°C | 116 mm | 75% | 0.2 m/s | 5.5 |
| 2019 | 14.7°C | 8.4°C | 2.0°C | 21.6°C | -4.3°C | 64 mm | 74% | 0.2 m/s | 5.5 |
| 2018 | 17.4°C | 11.0°C | 4.6°C | 23.6°C | -1.1°C | 100 mm | 78% | 0.2 m/s | 5.5 |
| 2017 | 15.2°C | 8.7°C | 2.1°C | 25.2°C | -2.6°C | 73 mm | 72% | 0.3 m/s | 5.9 |
| 2016 | 14.5°C | 8.4°C | 2.3°C | 22.5°C | -1.9°C | 90 mm | 73% | 0.3 m/s | 5.4 |
| 2015 | 15.5°C | 8.6°C | 1.8°C | 20.1°C | -3.5°C | 55 mm | 73% | 0.2 m/s | 5.8 |
| 2014 | 14.9°C | 8.6°C | 2.3°C | 22.6°C | -4.3°C | 49 mm | 72% | 0.3 m/s | 6 |
| 2013 | 15.1°C | 8.7°C | 2.3°C | 23.2°C | -3.9°C | 72 mm | 73% | 0.3 m/s | 5.6 |
| 2012 | 12.7°C | 6.8°C | 0.9°C | 24.4°C | -4.1°C | 76 mm | 70% | 0.3 m/s | 5.6 |
| 2011 | 11.3°C | 5.6°C | -0.1°C | 17.8°C | -4.6°C | 85 mm | 78% | 0.3 m/s | 5.1 |
| 2010 | 10.8°C | 5.2°C | -0.5°C | 21.9°C | -5.6°C | 99 mm | 74% | 0.2 m/s | 4.9 |
| 2009 | 14.1°C | 7.6°C | 1.2°C | 23.8°C | -5.1°C | 62 mm | 73% | 0.3 m/s | 6.1 |
| 2008 | 13.2°C | 7.3°C | 1.4°C | 23.8°C | -5.4°C | 75 mm | 77% | 0.3 m/s | 5.3 |
| 2007 | 15.0°C | 8.1°C | 1.2°C | 23.5°C | -8.7°C | 75 mm | 74% | 0.3 m/s | 5.9 |
| 2006 | 15.5°C | 9.0°C | 2.4°C | 26.9°C | -5.1°C | 57 mm | 69% | 0.3 m/s | 6.2 |
| 2005 | 14.5°C | 7.8°C | 1.1°C | 22.1°C | -4.8°C | 81 mm | 74% | 0.3 m/s | 5.3 |
| 2004 | 12.2°C | 6.6°C | 1.0°C | 19.3°C | -6.1°C | 118 mm | 76% | 0.2 m/s | 4.9 |
| 2003 | 13.6°C | 7.2°C | 0.9°C | 28.2°C | -5.2°C | 75 mm | 76% | 0.3 m/s | 5.2 |
| 2002 | 12.5°C | 6.2°C | -0.1°C | 24.1°C | -6.5°C | 73 mm | 73% | 0.3 m/s | 5.2 |
| 2001 | 15.8°C | 8.7°C | 1.7°C | 27.6°C | -5.5°C | 29 mm | 64% | 0.3 m/s | 6.4 |
| 2000 | 13.7°C | 7.6°C | 1.4°C | 19.2°C | -3.6°C | 60 mm | 72% | 0.2 m/s | 5.4 |
| 1999 | 12.6°C | 6.4°C | 0.1°C | 24.9°C | -5.2°C | 58 mm | 71% | 0.3 m/s | 5.9 |
| 1998 | 16.0°C | 8.8°C | 1.6°C | 23.1°C | -1.7°C | 107 mm | 72% | 0.2 m/s | 5.6 |
| 1997 | 15.5°C | 9.1°C | 2.6°C | 24.3°C | -3.1°C | 74 mm | 74% | 0.3 m/s | 6.2 |
| 1996 | 10.8°C | 5.3°C | -0.1°C | 18.2°C | -4.5°C | 91 mm | 79% | 0.2 m/s | 5.1 |
| 1995 | 14.3°C | 7.6°C | 0.9°C | 22.9°C | -4.2°C | 55 mm | 72% | 0.3 m/s | 5.9 |
| 1994 | 16.6°C | 9.5°C | 2.4°C | 25.7°C | -2.6°C | 77 mm | 70% | 0.3 m/s | 5.1 |
| 1993 | 18.0°C | 10.4°C | 2.8°C | 25.9°C | -3.6°C | 78 mm | 73% | 0.2 m/s | 5.7 |
| 1992 | 17.5°C | 10.2°C | 2.9°C | 23.8°C | -4.4°C | 38 mm | 61% | 0.3 m/s | 6.3 |
| 1991 | 12.8°C | 6.6°C | 0.4°C | 19.2°C | -4.8°C | 83 mm | 75% | 0.2 m/s | 4.8 |
| 1990 | 12.5°C | 6.3°C | 0.1°C | 21.5°C | -4.9°C | 100 mm | 75% | 0.3 m/s | 4.8 |
| 1989 | 13.0°C | 6.6°C | 0.3°C | 21.3°C | -4.8°C | 69 mm | 75% | 0.3 m/s | 4.9 |
| 1988 | 15.1°C | 8.2°C | 1.3°C | 27.1°C | -5.0°C | 94 mm | 70% | 0.3 m/s | 5.1 |
| 1987 | 17.1°C | 10.3°C | 3.5°C | 25.3°C | -3.0°C | 59 mm | 67% | 0.3 m/s | 5.2 |
| 1986 | 15.4°C | 8.4°C | 1.5°C | 30.1°C | -5.3°C | 60 mm | 71% | 0.3 m/s | 5.8 |
| 1985 | 16.6°C | 9.6°C | 2.6°C | 24.1°C | -6.1°C | 60 mm | 67% | 0.3 m/s | 5.8 |
| 1984 ❄️ | 11.4°C | 5.1°C | -1.3°C | 25.3°C | -4.7°C | 74 mm | 74% | 0.2 m/s | 5.3 |
| 1983 | 13.9°C | 7.2°C | 0.4°C | 27.0°C | -6.1°C | 64 mm | 71% | 0.3 m/s | — |
| 1982 | 12.6°C | 6.1°C | -0.3°C | 21.2°C | -5.4°C | 66 mm | 73% | 0.2 m/s | — |
| 1981 🌧️ | 13.3°C | 7.1°C | 0.9°C | 20.5°C | -4.1°C | 123 mm | 77% | 0.3 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 14.3°C with lows near 1.4°C (mean 7.9°C), based on 45 years of NASA POWER data.
May averages 76 mm of rainfall in Missoula, a relatively wet time of year. The wettest on record was 123 mm in 1981.
The hottest May reached 30.1°C in 1986. The coldest dipped to -8.7°C in 2007.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 1.3°C. Daytime highs moved from 13.6°C to 14.6°C and overnight lows from 0.5°C to 1.9°C over the same span.
May is one of the warmer months of the year in Missoula and a relatively wet time of year, so plan for around 14.3°C daytime highs and 1.4°C at night.
Not quite — May is the 8th coolest month in Missoula, averaging 7.9°C.
For May in Missoula, pack warm layers and a jacket for chilly mornings, with typical highs of 14.3°C and lows of 1.4°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 73% — moderately humid.
Average wind speed in May is 0.3 m/s. The windiest May on record averaged 0.3 m/s (1981).
The wettest May on record was 1981 with 123 mm. On average, May sees 76 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Missoula behaves each May, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for May specifically, along with year-by-year records and how the month has changed over the decades.
