May is one of the warmer months of the year in Idaho Falls, with average highs near 17.6°C and lows around 3.6°C (mean 10.6°C). It is a relatively wet time of year, averaging 58 mm of rainfall and 58% relative humidity across the period.
May is one of the warmer months of the year in Idaho Falls. Across 45 years of records, the warmest May in Idaho Falls was 1992 — when the month averaged 14.3°C — while the coldest was 2010 at 6.6°C. Typical May days reach 17.6°C with nights near 3.6°C. The long-term May temperature trend is broadly flat.
May is a relatively wet time of year in Idaho Falls, averaging 58 mm of rainfall. The wettest May on record was 1981 with 119 mm, while the driest was 1992 at 12 mm.
Relative humidity in Idaho Falls during May averages 58%. The most humid May was 2011 at 67%, and the least humid was 2001 at 40%.
May receives about 6.3 kWh/m²/day of solar energy in Idaho Falls. The sunniest May was 2001 at 7.5 kWh/m²/day, and the cloudiest was 2010 at 5.2.
Average wind speed in Idaho Falls during May is 2.6 m/s. The windiest May was 1984 at 3.3 m/s, while the calmest was 2018 at 2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 10.3°C | 10.6°C | 11.2°C | 10.2°C | 10.6°C | +0.3°C |
| Avg High | 17.5°C | 17.6°C | 18.4°C | 16.9°C | 17.4°C | -0.1°C |
| Avg Low | 3.1°C | 3.7°C | 4.0°C | 3.5°C | 3.8°C | +0.7°C |
| Avg Rain | 56 mm | 69 mm | 45 mm | 63 mm | 56 mm | -1 mm |
May temperatures in Idaho Falls have risen by about 0.8°C between 1981–1985 and 2021–2025.
May has ranged from a record low of -5.9°C (2019) to a record high of 33.4°C (2003).
Rainfall in May is a relatively wet time of year, averaging 58 mm, with a wettest year of 119 mm.
Daytime highs and overnight lows have shifted differently — highs fell about 0.1°C per decade while lows rose 0.2°C per decade, narrowing the gap between day and night.
A good time to visit Idaho Falls
May is a good time to visit Idaho Falls, with days averaging 17.6°C and nights around 3.6°C (mean 10.6°C, warmer than Idaho Falls'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 | 19.7°C | 12.5°C | 5.4°C | 29.1°C | 0.2°C | 57 mm | 56% | 2.3 m/s | 6.5 |
| 2024 | 15.4°C | 8.5°C | 1.6°C | 25.9°C | -5.2°C | 50 mm | 60% | 2.9 m/s | 6.4 |
| 2023 | 18.5°C | 12.1°C | 5.8°C | 25.6°C | -0.5°C | 55 mm | 66% | 2.2 m/s | 6.1 |
| 2022 | 15.1°C | 8.6°C | 2.1°C | 27.8°C | -4.2°C | 58 mm | 60% | 2.8 m/s | 5.9 |
| 2021 | 18.2°C | 11.0°C | 3.8°C | 24.9°C | -4.4°C | 62 mm | 54% | 2.4 m/s | 6.5 |
| 2020 | 17.6°C | 10.7°C | 3.8°C | 30.1°C | -2.9°C | 52 mm | 61% | 2.8 m/s | 6.5 |
| 2019 | 15.5°C | 9.4°C | 3.2°C | 23.5°C | -5.9°C | 68 mm | 65% | 2.3 m/s | 5.6 |
| 2018 | 19.1°C | 12.6°C | 6.0°C | 26.7°C | -2.0°C | 76 mm | 66% | 2 m/s | 6.1 |
| 2017 | 17.3°C | 10.4°C | 3.5°C | 25.9°C | -2.3°C | 28 mm | 63% | 2.2 m/s | 6.7 |
| 2016 | 17.6°C | 10.7°C | 3.7°C | 24.3°C | -1.9°C | 70 mm | 60% | 2.4 m/s | 6.4 |
| 2015 | 17.2°C | 10.9°C | 4.6°C | 26.5°C | -1.5°C | 116 mm | 65% | 2.1 m/s | 5.5 |
| 2014 | 19.0°C | 11.8°C | 4.5°C | 27.4°C | -4.1°C | 26 mm | 55% | 2.5 m/s | 6.9 |
| 2013 | 18.2°C | 11.3°C | 4.4°C | 28.3°C | -4.5°C | 40 mm | 57% | 2.4 m/s | 6.2 |
| 2012 | 18.2°C | 10.9°C | 3.6°C | 28.1°C | -2.7°C | 51 mm | 53% | 2.6 m/s | 6.5 |
| 2011 | 13.6°C | 7.6°C | 1.5°C | 21.9°C | -3.7°C | 90 mm | 67% | 2.7 m/s | 5.3 |
| 2010 ❄️ | 12.9°C | 6.6°C | 0.2°C | 24.1°C | -5.1°C | 62 mm | 61% | 2.7 m/s | 5.2 |
| 2009 | 17.7°C | 10.7°C | 3.7°C | 28.1°C | -5.0°C | 46 mm | 58% | 2.5 m/s | 6.8 |
| 2008 | 16.0°C | 9.2°C | 2.4°C | 27.8°C | -4.6°C | 67 mm | 62% | 2.3 m/s | 5.9 |
| 2007 | 20.0°C | 12.4°C | 4.8°C | 27.5°C | -3.7°C | 15 mm | 48% | 2.9 m/s | 6.9 |
| 2006 | 18.6°C | 11.4°C | 4.3°C | 27.5°C | -3.5°C | 34 mm | 57% | 2.6 m/s | 6.9 |
| 2005 | 17.3°C | 10.4°C | 3.5°C | 24.5°C | -3.0°C | 92 mm | 62% | 2.5 m/s | 6 |
| 2004 | 17.2°C | 10.6°C | 4.1°C | 25.1°C | -1.1°C | 63 mm | 55% | 3.1 m/s | 5.8 |
| 2003 | 18.8°C | 11.7°C | 4.6°C | 33.4°C | -4.4°C | 33 mm | 52% | 2.5 m/s | 6.7 |
| 2002 | 18.2°C | 10.8°C | 3.5°C | 30.5°C | -4.6°C | 38 mm | 48% | 2.9 m/s | 6.5 |
| 2001 | 21.7°C | 13.3°C | 4.9°C | 30.3°C | -4.5°C | 16 mm | 40% | 3 m/s | 7.5 |
| 2000 | 18.7°C | 11.6°C | 4.6°C | 26.1°C | -4.0°C | 48 mm | 54% | 3 m/s | 6.2 |
| 1999 | 15.4°C | 8.8°C | 2.3°C | 26.5°C | -5.0°C | 83 mm | 60% | 2.5 m/s | 6.1 |
| 1998 | 16.7°C | 9.8°C | 3.0°C | 23.4°C | -2.8°C | 83 mm | 62% | 2.5 m/s | 6.2 |
| 1997 | 18.7°C | 11.5°C | 4.4°C | 28.7°C | -4.5°C | 56 mm | 60% | 2.2 m/s | 6.7 |
| 1996 | 15.2°C | 8.8°C | 2.4°C | 24.2°C | -3.1°C | 90 mm | 62% | 2.8 m/s | 6.1 |
| 1995 | 15.2°C | 8.9°C | 2.5°C | 23.3°C | -1.4°C | 82 mm | 66% | 2.2 m/s | 6.1 |
| 1994 | 20.8°C | 13.2°C | 5.7°C | 27.3°C | 1.0°C | 44 mm | 52% | 2.7 m/s | 6.1 |
| 1993 | 19.2°C | 12.1°C | 5.1°C | 25.5°C | -3.4°C | 92 mm | 61% | 2.3 m/s | 6.1 |
| 1992 🔥 | 22.1°C | 14.3°C | 6.5°C | 27.8°C | 0.2°C | 12 mm | 43% | 2.5 m/s | 6.6 |
| 1991 | 16.0°C | 9.2°C | 2.5°C | 22.6°C | -3.1°C | 103 mm | 60% | 2.5 m/s | 5.6 |
| 1990 | 16.2°C | 9.2°C | 2.3°C | 25.1°C | -5.7°C | 51 mm | 54% | 2.8 m/s | 6 |
| 1989 | 17.7°C | 10.3°C | 3.0°C | 24.9°C | -4.1°C | 41 mm | 54% | 2.6 m/s | 6.2 |
| 1988 | 18.9°C | 11.2°C | 3.4°C | 28.2°C | -5.5°C | 30 mm | 49% | 3 m/s | 6.5 |
| 1987 | 19.8°C | 12.9°C | 5.9°C | 29.1°C | -2.0°C | 90 mm | 55% | 2.4 m/s | 6.2 |
| 1986 | 17.2°C | 9.8°C | 2.3°C | 28.0°C | -4.4°C | 49 mm | 58% | 2.7 m/s | 6.6 |
| 1985 | 19.7°C | 12.1°C | 4.4°C | 26.7°C | -5.4°C | 48 mm | 51% | 2.6 m/s | 6.2 |
| 1984 | 16.2°C | 9.2°C | 2.2°C | 28.1°C | -3.8°C | 37 mm | 61% | 3.3 m/s | 5.8 |
| 1983 | 15.2°C | 8.3°C | 1.3°C | 27.6°C | -5.3°C | 43 mm | 61% | 2.4 m/s | — |
| 1982 | 16.1°C | 8.9°C | 1.6°C | 24.2°C | -5.5°C | 51 mm | 59% | 2.4 m/s | — |
| 1981 🌧️ | 16.6°C | 10.1°C | 3.6°C | 25.9°C | -2.5°C | 119 mm | 61% | 2.5 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 17.6°C with lows near 3.6°C (mean 10.6°C), based on 45 years of NASA POWER data.
May averages 58 mm of rainfall in Idaho Falls, a relatively wet time of year. The wettest on record was 119 mm in 1981.
The hottest May reached 33.4°C in 2003. The coldest dipped to -5.9°C in 2019.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 0.8°C. Daytime highs moved from 16.8°C to 17.4°C and overnight lows from 2.6°C to 3.7°C over the same span.
May is one of the warmer months of the year in Idaho Falls and a relatively wet time of year, so plan for around 17.6°C daytime highs and 3.6°C at night.
Not quite — May is the 8th coolest month in Idaho Falls, averaging 10.6°C.
For May in Idaho Falls, pack warm layers and a jacket for chilly mornings, with typical highs of 17.6°C and lows of 3.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 58% — moderately humid.
Average wind speed in May is 2.6 m/s. The windiest May on record averaged 3.3 m/s (1984).
The wettest May on record was 1981 with 119 mm. On average, May sees 58 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 Idaho Falls 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.
