Climate averages 1991–2020
Nampa weather
in December.
A cold, moderately wet month: the coolest and the wettest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a cold month in Nampa: daytime highs average 4.4°C and nights cool to about -2.9°C. By daytime temperature it is the coolest month of the year.
Expect about 42 mm of rain on roughly 9 days, which makes December a moderately wet month (the wettest month of the year). Daylight, from sunrise to sunset, lasts about 9 h 01 min on an average December day.
The nearest other city in this atlas is Meridian (16 km away). In December its highs average 3.6°C, 0.7°C cooler than Nampa, with 42 mm of rain.
Among the 498 cities listed in the United States, Nampa ranks joint 379th of 498 for the warmest December highs and joint 90th of 498 for the driest December (rainfall, lowest first). The mean December high of those 498 cities is 10.5°C; Nampa is 6.2°C cooler than that mean.
From December to January, average highs rise by 0.2°C to 4.6°C, and monthly rainfall falls from 42 mm to 40 mm.
The annual picture
December 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 | 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, selected | 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
December in nearby cities
- Meridian in DecemberUnited States · 16 kmHigh 3.6°C · Low -3.8°C · 42 mm rain
- Boise in DecemberUnited States · 30 kmHigh 3.7°C · Low -4.1°C · 50 mm rain
- Kennewick in DecemberUnited States · 360 kmHigh 5.4°C · Low -1.4°C · 35 mm rain
- Tri-Cities in DecemberUnited States · 365 kmHigh 5.6°C · Low -1.2°C · 35 mm rain
- Bend in DecemberUnited States · 386 kmHigh 3.2°C · Low -4.9°C · 96 mm rain
- Missoula in DecemberUnited States · 422 kmHigh -0.1°C · Low -7.4°C · 51 mm precipitation
- Ogden in DecemberUnited States · 457 kmHigh 1.8°C · Low -7.9°C · 55 mm precipitation
- Yakima in DecemberUnited States · 460 kmHigh 2.5°C · Low -4.0°C · 66 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.