May is one of the warmer months of the year in Nampa, with average highs near 21.9°C and lows around 7.4°C (mean 14.7°C). It is about average for rainfall, averaging 38 mm of rainfall and 49% relative humidity across the period.
May is one of the warmer months of the year in Nampa. Across 45 years of records, the warmest May in Nampa was 1992 — when the month averaged 18.2°C — while the coldest was 2010 at 11°C. Typical May days reach 21.9°C with nights near 7.4°C. The long-term trend is warming, about 0.3°C per decade.
May is about average for rainfall in Nampa, averaging 38 mm of rainfall. The wettest May on record was 1998 with 128 mm, while the driest was 1992 at 6 mm.
Relative humidity in Nampa during May averages 49%. The most humid May was 1998 at 61%, and the least humid was 1992 at 36%.
May receives about 6.7 kWh/m²/day of solar energy in Nampa. The sunniest May was 1992 at 7.6 kWh/m²/day, and the cloudiest were 1994, 1998 and 2010 at 5.9.
Average wind speed in Nampa during May is 2.3 m/s. The windiest May was 1991 at 2.7 m/s, while the calmest was 2023 at 1.8 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 14.1°C | 14.5°C | 15.4°C | 14.6°C | 14.9°C | +0.8°C |
| Avg High | 21.4°C | 21.7°C | 22.9°C | 21.6°C | 22.1°C | +0.7°C |
| Avg Low | 6.7°C | 7.3°C | 7.9°C | 7.5°C | 7.7°C | +1°C |
| Avg Rain | 31 mm | 49 mm | 34 mm | 34 mm | 41 mm | +10 mm |
May temperatures in Nampa have risen by about 1.5°C between 1981–1985 and 2021–2025.
May has ranged from a record low of -3.4°C (1999) to a record high of 38.4°C (2003).
Rainfall in May is about average for rainfall, averaging 38 mm, with a wettest year of 128 mm.
A good time to visit Nampa
May is a good time to visit Nampa, with days averaging 21.9°C and nights around 7.4°C (mean 14.7°C, warmer than Nampa's yearly average) and moderate rainfall. June 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 | 24.1°C | 16.1°C | 8.2°C | 38.4°C | 2.0°C | 23 mm | 48% | 2.4 m/s | 7.1 |
| 2024 | 21.1°C | 13.6°C | 6.1°C | 31.0°C | 0.6°C | 33 mm | 51% | 2.5 m/s | 7.2 |
| 2023 | 23.9°C | 17.1°C | 10.3°C | 32.6°C | 4.4°C | 50 mm | 52% | 1.8 m/s | 6.5 |
| 2022 | 19.4°C | 12.8°C | 6.2°C | 31.2°C | -0.9°C | 60 mm | 53% | 2.5 m/s | 6.2 |
| 2021 | 22.0°C | 14.7°C | 7.4°C | 32.9°C | 2.0°C | 21 mm | 45% | 2.5 m/s | 7 |
| 2020 | 22.2°C | 15.1°C | 7.9°C | 38.1°C | 2.6°C | 59 mm | 47% | 2.2 m/s | 6.6 |
| 2019 | 21.0°C | 14.6°C | 8.1°C | 30.8°C | 0.3°C | 66 mm | 55% | 1.9 m/s | 6.3 |
| 2018 | 23.9°C | 17.1°C | 10.3°C | 29.6°C | 2.1°C | 38 mm | 54% | 2.1 m/s | 6.5 |
| 2017 | 22.3°C | 14.8°C | 7.2°C | 33.5°C | 0.5°C | 23 mm | 51% | 2.3 m/s | 7 |
| 2016 | 22.8°C | 15.5°C | 8.2°C | 30.2°C | 3.5°C | 30 mm | 49% | 2.3 m/s | 6.8 |
| 2015 | 22.4°C | 15.7°C | 9.1°C | 33.1°C | 3.3°C | 41 mm | 52% | 2.1 m/s | 6.3 |
| 2014 | 23.3°C | 15.6°C | 8.0°C | 30.8°C | 1.0°C | 16 mm | 45% | 2.4 m/s | 7.3 |
| 2013 | 23.4°C | 15.9°C | 8.4°C | 34.2°C | -1.4°C | 16 mm | 42% | 2.3 m/s | 6.9 |
| 2012 | 21.8°C | 14.3°C | 6.8°C | 31.7°C | -0.9°C | 20 mm | 44% | 2.3 m/s | 6.8 |
| 2011 | 18.1°C | 11.4°C | 4.7°C | 28.5°C | -1.8°C | 48 mm | 58% | 2.6 m/s | 6.1 |
| 2010 ❄️ | 17.3°C | 11.0°C | 4.6°C | 29.1°C | -1.3°C | 45 mm | 52% | 2.6 m/s | 5.9 |
| 2009 | 23.8°C | 16.0°C | 8.3°C | 36.3°C | 0.3°C | 37 mm | 43% | 2.2 m/s | 7.1 |
| 2008 | 22.2°C | 14.8°C | 7.4°C | 34.5°C | -1.0°C | 25 mm | 47% | 2.4 m/s | 6.7 |
| 2007 | 24.3°C | 16.3°C | 8.3°C | 32.2°C | 0.6°C | 10 mm | 41% | 2.4 m/s | 7.4 |
| 2006 | 23.1°C | 15.5°C | 7.9°C | 33.5°C | -1.0°C | 35 mm | 49% | 2.1 m/s | 7.1 |
| 2005 | 21.8°C | 14.9°C | 8.0°C | 31.5°C | 2.5°C | 86 mm | 54% | 2.2 m/s | 6 |
| 2004 | 21.4°C | 14.5°C | 7.6°C | 32.2°C | 1.7°C | 57 mm | 50% | 2.2 m/s | 6.3 |
| 2003 | 22.4°C | 15.0°C | 7.7°C | 38.4°C | 0.2°C | 41 mm | 50% | 2.1 m/s | 6.8 |
| 2002 | 22.2°C | 14.5°C | 6.9°C | 34.0°C | -2.0°C | 10 mm | 43% | 2.4 m/s | 7.1 |
| 2001 | 25.0°C | 16.8°C | 8.6°C | 36.1°C | -1.4°C | 15 mm | 39% | 2.3 m/s | 7.3 |
| 2000 | 22.4°C | 15.4°C | 8.3°C | 31.0°C | 0.7°C | 27 mm | 48% | 2.4 m/s | 6.4 |
| 1999 | 20.6°C | 13.0°C | 5.4°C | 33.0°C | -3.4°C | 19 mm | 46% | 2.5 m/s | 7.2 |
| 1998 🌧️ | 18.8°C | 12.8°C | 6.8°C | 28.7°C | 2.0°C | 128 mm | 61% | 2 m/s | 5.9 |
| 1997 | 24.9°C | 17.1°C | 9.4°C | 31.8°C | 0.4°C | 30 mm | 48% | 1.9 m/s | 7.1 |
| 1996 | 19.5°C | 12.7°C | 5.9°C | 27.7°C | -1.4°C | 52 mm | 55% | 2.3 m/s | 6.6 |
| 1995 | 20.0°C | 13.4°C | 6.8°C | 29.6°C | 0.9°C | 68 mm | 57% | 2.2 m/s | 6.3 |
| 1994 | 23.2°C | 16.0°C | 8.9°C | 31.7°C | 2.5°C | 39 mm | 50% | 1.9 m/s | 5.9 |
| 1993 | 24.4°C | 16.7°C | 9.0°C | 31.7°C | 0.7°C | 29 mm | 52% | 2.3 m/s | 6.5 |
| 1992 🔥 | 26.6°C | 18.2°C | 9.8°C | 32.4°C | 2.7°C | 6 mm | 36% | 2.2 m/s | 7.6 |
| 1991 | 19.2°C | 12.2°C | 5.3°C | 27.0°C | 2.2°C | 61 mm | 52% | 2.7 m/s | 6 |
| 1990 | 20.0°C | 13.1°C | 6.1°C | 30.9°C | 0.8°C | 58 mm | 49% | 2.4 m/s | 6.6 |
| 1989 | 21.1°C | 13.6°C | 6.2°C | 31.4°C | 1.3°C | 18 mm | 50% | 2.4 m/s | 6.9 |
| 1988 | 22.1°C | 14.6°C | 7.0°C | 33.7°C | -0.8°C | 29 mm | 44% | 2.5 m/s | 6.5 |
| 1987 | 24.2°C | 16.8°C | 9.5°C | 33.9°C | 1.8°C | 43 mm | 43% | 2.2 m/s | 6.6 |
| 1986 | 22.1°C | 14.5°C | 6.8°C | 36.0°C | 0.0°C | 28 mm | 51% | 2.4 m/s | 6.6 |
| 1985 | 22.7°C | 15.2°C | 7.7°C | 32.1°C | -1.0°C | 39 mm | 47% | 2.2 m/s | 6.9 |
| 1984 | 20.2°C | 12.8°C | 5.3°C | 34.8°C | 0.0°C | 28 mm | 55% | 2.4 m/s | 6.2 |
| 1983 | 20.3°C | 13.4°C | 6.5°C | 35.3°C | -0.7°C | 34 mm | 57% | 2.3 m/s | — |
| 1982 | 20.3°C | 12.9°C | 5.4°C | 29.9°C | 0.0°C | 19 mm | 52% | 2.5 m/s | — |
| 1981 | 19.7°C | 12.7°C | 5.8°C | 28.3°C | -0.2°C | 42 mm | 55% | 2.4 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 21.9°C with lows near 7.4°C (mean 14.7°C), based on 45 years of NASA POWER data.
May averages 38 mm of rainfall in Nampa, about average for rainfall. The wettest on record was 128 mm in 1998.
The hottest May reached 38.4°C in 2003. The coldest dipped to -3.4°C in 1999.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 1.5°C. Daytime highs moved from 20.6°C to 22.1°C and overnight lows from 6.1°C to 7.6°C over the same span.
May is one of the warmer months of the year in Nampa and about average for rainfall, so plan for around 21.9°C daytime highs and 7.4°C at night.
Not quite — May is the 8th coolest month in Nampa, averaging 14.7°C.
For May in Nampa, pack warm layers and a jacket for chilly mornings, with typical highs of 21.9°C and lows of 7.4°C.
Relative humidity in May averages 49% — relatively dry.
Average wind speed in May is 2.3 m/s. The windiest May on record averaged 2.7 m/s (1991).
The wettest May on record was 1998 with 128 mm. On average, May sees 38 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 Nampa 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.
