Climate averages 1991–2020
Boise 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 Boise: daytime highs average 3.7°C and nights cool to about -4.1°C. By daytime temperature it is the coolest month of the year.
Expect about 50 mm of rain on roughly 10 days, which makes December a moderately wet month (the wettest month of the year). Daylight, from sunrise to sunset, lasts about 9 h 00 min on an average December day.
The nearest other city in this atlas is Meridian (15 km away). In December its highs average 3.6°C, about as warm as Boise, with 42 mm of rain.
Among the 498 cities listed in the United States, Boise ranks joint 402nd of 498 for the warmest December highs and joint 139th of 498 for the driest December (rainfall, lowest first). The mean December high of those 498 cities is 10.5°C; Boise is 6.8°C cooler than that mean.
From December to January, average highs rise by 0.1°C to 3.8°C, and monthly rainfall falls from 50 mm to 45 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
Boise climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 3.8°C-4.6°C | -4.6°C | 45 | 9.5 | 9.39 h |
| February | 6.8°C-2.5°C | -2.5°C | 31 | 7.7 | 10.510 h |
| March | 11.9°C0.9°C | 0.9°C | 36 | 8.9 | 11.912 h |
| April | 15.9°C3.8°C | 3.8°C | 31 | 7.2 | 13.413 h |
| May | 21.6°C8.5°C | 8.5°C | 31 | 5.9 | 14.715 h |
| June | 26.5°C13.0°C | 13.0°C | 16 | 3.2 | 15.415 h |
| July | 32.7°C17.9°C | 17.9°C | 2.6 | 0.9 | 15.115 h |
| August | 31.9°C17.4°C | 17.4°C | 3.3 | 0.7 | 14.014 h |
| September | 26.2°C12.6°C | 12.6°C | 10 | 2.2 | 12.613 h |
| October | 17.7°C6.3°C | 6.3°C | 22 | 4.3 | 11.111 h |
| November | 9.3°C0.2°C | 0.2°C | 34 | 7.9 | 9.710 h |
| December, selected | 3.7°C-4.1°C | -4.1°C | 50 | 10.1 | 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 · 15 kmHigh 3.6°C · Low -3.8°C · 42 mm rain
- Nampa in DecemberUnited States · 30 kmHigh 4.4°C · Low -2.9°C · 42 mm rain
- Kennewick in DecemberUnited States · 370 kmHigh 5.4°C · Low -1.4°C · 35 mm rain
- Tri-Cities in DecemberUnited States · 376 kmHigh 5.6°C · Low -1.2°C · 35 mm rain
- Missoula in DecemberUnited States · 401 kmHigh -0.1°C · Low -7.4°C · 51 mm precipitation
- Bend in DecemberUnited States · 413 kmHigh 3.2°C · Low -4.9°C · 96 mm rain
- Ogden in DecemberUnited States · 437 kmHigh 1.8°C · Low -7.9°C · 55 mm precipitation
- Layton in DecemberUnited States · 449 kmHigh 1.8°C · Low -7.6°C · 51 mm precipitation
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 Boise) is explained once on the Boise year overview and on the Sources, method and limits page.