Climate averages 1991–2020
Rapid City weather
in December.
A cold, fairly dry month: the 11th warmest and the 2nd driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a cold month in Rapid City: daytime highs average 2.8°C and nights cool to about -6.9°C. By daytime temperature it is the 11th warmest of the 12 months.
Expect about 15 mm of rain on roughly 4 days, which makes December a fairly dry month (the 2nd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 8 h 57 min on an average December day.
The nearest other city in this atlas is Bismarck (358 km away). In December its highs average -3.4°C, 6.2°C cooler than Rapid City, with 18 mm of precipitation.
Among the 498 cities listed in the United States, Rapid City ranks joint 420th of 498 for the warmest December highs and 6th of 498 for the driest December (rainfall, lowest first). The mean December high of those 498 cities is 10.5°C; Rapid City is 7.7°C cooler than that mean.
From December to January, average highs fall by 0.3°C to 2.5°C, and monthly rainfall falls from 15 mm to 13 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
Rapid City climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 2.5°C-8.1°C | -8.1°C | 13 | 3.9 | 9.39 h |
| February | 3.5°C-7.6°C | -7.6°C | 20 | 5.1 | 10.410 h |
| March | 8.5°C-3.5°C | -3.5°C | 40 | 7.6 | 11.912 h |
| April | 12.8°C1.1°C | 1.1°C | 80 | 11.8 | 13.413 h |
| May | 18.4°C7.2°C | 7.2°C | 112 | 14.1 | 14.715 h |
| June | 24.4°C12.9°C | 12.9°C | 97 | 14.5 | 15.415 h |
| July | 28.9°C16.9°C | 16.9°C | 78 | 13.4 | 15.115 h |
| August | 28.2°C16.1°C | 16.1°C | 60 | 10.8 | 14.014 h |
| September | 23.3°C11.2°C | 11.2°C | 42 | 6.7 | 12.613 h |
| October | 14.9°C3.9°C | 3.9°C | 50 | 7.3 | 11.011 h |
| November | 7.9°C-2.5°C | -2.5°C | 20 | 4.4 | 9.710 h |
| December, selected | 2.8°C-6.9°C | -6.9°C | 15 | 3.6 | 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
- Bismarck in DecemberUnited States · 358 kmHigh -3.4°C · Low -11.4°C · 18 mm precipitation
- Fort Collins in DecemberUnited States · 417 kmHigh 4.2°C · Low -7.8°C · 16 mm rain
- Greeley in DecemberUnited States · 424 kmHigh 4.9°C · Low -6.8°C · 11 mm rain
- Loveland in DecemberUnited States · 437 kmHigh 4.2°C · Low -8.4°C · 16 mm rain
- Billings in DecemberUnited States · 456 kmHigh 1.8°C · Low -7.5°C · 20 mm precipitation
- Longmont in DecemberUnited States · 462 kmHigh 4.2°C · Low -8.1°C · 18 mm rain
- Boulder in DecemberUnited States · 482 kmHigh 4.0°C · Low -8.8°C · 23 mm rain
- Thornton in DecemberUnited States · 490 kmHigh 4.0°C · Low -9.7°C · 21 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 Rapid City) is explained once on the Rapid City year overview and on the Sources, method and limits page.