Climate averages 1991–2020
Nampa weather
in May.
A warm, fairly dry month: the 5th warmest and the 8th driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
May is a warm month in Nampa: daytime highs average 22.4°C and nights cool to about 9.8°C. By daytime temperature it is the 5th warmest of the 12 months.
Expect about 29 mm of rain on roughly 6 days, which makes May a fairly dry month (the 8th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 14 h 41 min on an average May day.
The nearest other city in this atlas is Meridian (16 km away). In May its highs average 21.8°C, 0.7°C cooler than Nampa, with 29 mm of rain.
Among the 498 cities listed in the United States, Nampa ranks joint 281st of 498 for the warmest May highs and joint 125th of 498 for the driest May (rainfall, lowest first). The mean May high of those 498 cities is 23.8°C; Nampa is 1.4°C cooler than that mean.
From May to June, average highs rise by 4.9°C to 27.3°C, and monthly rainfall falls from 29 mm to 16 mm.
The annual picture
May in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Nampa climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 4.6°C-3.4°C | -3.4°C | 40 | 9.0 | 9.39 h |
| February | 7.7°C-1.9°C | -1.9°C | 26 | 7.4 | 10.510 h |
| March | 12.8°C1.5°C | 1.5°C | 31 | 8.6 | 11.912 h |
| April | 16.8°C4.7°C | 4.7°C | 28 | 6.4 | 13.413 h |
| May, selected | 22.4°C9.8°C | 9.8°C | 29 | 5.9 | 14.715 h |
| June | 27.3°C14.2°C | 14.2°C | 16 | 3.4 | 15.415 h |
| July | 33.3°C19.2°C | 19.2°C | 3.4 | 1.0 | 15.115 h |
| August | 32.3°C18.3°C | 18.3°C | 3.4 | 0.9 | 14.014 h |
| September | 26.5°C13.4°C | 13.4°C | 9.8 | 2.0 | 12.613 h |
| October | 18.2°C6.9°C | 6.9°C | 20 | 4.2 | 11.111 h |
| November | 9.9°C0.9°C | 0.9°C | 30 | 7.3 | 9.710 h |
| December | 4.4°C-2.9°C | -2.9°C | 42 | 9.3 | 9.09 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
May in nearby cities
- Meridian in MayUnited States · 16 kmHigh 21.8°C · Low 8.6°C · 29 mm rain
- Boise in MayUnited States · 30 kmHigh 21.6°C · Low 8.5°C · 31 mm rain
- Kennewick in MayUnited States · 360 kmHigh 24.8°C · Low 11.4°C · 18 mm rain
- Tri-Cities in MayUnited States · 365 kmHigh 25.0°C · Low 11.5°C · 18 mm rain
- Bend in MayUnited States · 386 kmHigh 16.9°C · Low 4.4°C · 45 mm rain
- Missoula in MayUnited States · 422 kmHigh 17.9°C · Low 6.3°C · 56 mm rain
- Ogden in MayUnited States · 457 kmHigh 19.6°C · Low 7.4°C · 59 mm rain
- Yakima in MayUnited States · 460 kmHigh 21.4°C · Low 7.8°C · 18 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Nampa) is explained once on the Nampa year overview and on the Sources, method and limits page.
Meridian lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.