December is one of the cooler months of the year in Nampa, with average highs near 3.8°C and lows around -4.1°C (mean -0.1°C). It is a relatively wet time of year, averaging 49 mm of rainfall and 76% relative humidity across the period.
December is one of the cooler months of the year in Nampa. Across 45 years of records, the warmest December in Nampa was 2025 — when the month averaged 5.5°C — while the coldest was 1985 at -5.2°C. Typical December days reach 3.8°C with nights near -4.1°C. The long-term trend is warming, about 0.7°C per decade.
December is a relatively wet time of year in Nampa, averaging 49 mm of rainfall. The wettest December on record was 1996 with 123 mm, while the driest was 1989 at 4 mm.
Relative humidity in Nampa during December averages 76%. The most humid December was 1985 at 90%, and the least humid was 1990 at 64%.
December receives about 1.4 kWh/m²/day of solar energy in Nampa. The sunniest December was 2011 at 1.9 kWh/m²/day, and the cloudiest was 2015 at 1.1.
Average wind speed in Nampa during December is 2.2 m/s. The windiest December was 1996 at 3.1 m/s, while the calmest was 1985 at 1.4 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -1.4°C | -0.6°C | 0.3°C | 0.0°C | 1.8°C | +3.2°C |
| Avg High | 2.5°C | 3.4°C | 4.2°C | 3.9°C | 6.0°C | +3.5°C |
| Avg Low | -5.3°C | -4.5°C | -3.6°C | -4.0°C | -2.3°C | +3°C |
| Avg Rain | 44 mm | 44 mm | 52 mm | 48 mm | 61 mm | +17 mm |
December temperatures in Nampa have risen by about 4.5°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -23.7°C (1990) to a record high of 17.2°C (2021).
Rainfall in December is a relatively wet time of year, averaging 49 mm, with a wettest year of 123 mm.
A quieter season to visit Nampa
If your dates are flexible, the more temperate months of June and August tend to be the most comfortable for visiting Nampa. That said, December — with days averaging 3.8°C and nights around -4.1°C (mean -0.1°C) and moderate rainfall (49 mm) — can still be rewarding for travellers who don't mind the cooler conditions, and often means fewer crowds.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 🔥 | 10.3°C | 5.5°C | 0.8°C | 16.5°C | -4.2°C | 69 mm | 70% | 2.5 m/s | — |
| 2024 | 6.5°C | 2.8°C | -1.0°C | 11.6°C | -3.7°C | 87 mm | 77% | 2 m/s | 1.3 |
| 2023 | 6.1°C | 2.4°C | -1.4°C | 16.5°C | -4.8°C | 52 mm | 81% | 1.8 m/s | 1.3 |
| 2022 | 2.1°C | -1.9°C | -5.9°C | 10.8°C | -14.5°C | 77 mm | 82% | 2.4 m/s | 1.3 |
| 2021 | 5.9°C | 1.6°C | -2.7°C | 17.2°C | -15.1°C | 59 mm | 70% | 2.5 m/s | 1.2 |
| 2020 | 4.9°C | 0.5°C | -3.8°C | 15.1°C | -6.8°C | 23 mm | 70% | 2 m/s | 1.6 |
| 2019 | 5.8°C | 2.0°C | -1.9°C | 14.7°C | -6.6°C | 35 mm | 75% | 2.1 m/s | 1.2 |
| 2018 | 4.0°C | 0.0°C | -4.0°C | 11.1°C | -10.0°C | 43 mm | 76% | 2.4 m/s | 1.4 |
| 2017 | 2.3°C | -1.1°C | -4.5°C | 9.8°C | -10.7°C | 20 mm | 75% | 1.7 m/s | 1.3 |
| 2016 | 0.9°C | -3.4°C | -7.8°C | 8.8°C | -17.2°C | 61 mm | 78% | 2.3 m/s | 1.4 |
| 2015 | 3.2°C | -0.4°C | -4.0°C | 13.3°C | -12.9°C | 74 mm | 80% | 2.8 m/s | 1.1 |
| 2014 | 7.2°C | 3.0°C | -1.2°C | 15.6°C | -13.2°C | 78 mm | 75% | 2.4 m/s | 1.2 |
| 2013 | 2.6°C | -1.6°C | -5.8°C | 10.3°C | -15.7°C | 16 mm | 71% | 1.9 m/s | 1.5 |
| 2012 | 4.5°C | 0.8°C | -2.9°C | 13.7°C | -10.6°C | 47 mm | 70% | 2.8 m/s | 1.4 |
| 2011 | 4.3°C | -0.1°C | -4.5°C | 12.4°C | -8.1°C | 16 mm | 68% | 1.8 m/s | 1.9 |
| 2010 | 4.3°C | 0.7°C | -3.0°C | 12.4°C | -13.5°C | 87 mm | 82% | 2.5 m/s | 1.3 |
| 2009 | 1.3°C | -2.5°C | -6.3°C | 6.8°C | -13.9°C | 48 mm | 74% | 1.9 m/s | 1.6 |
| 2008 | 3.8°C | -0.2°C | -4.3°C | 12.5°C | -10.8°C | 53 mm | 69% | 2.7 m/s | 1.4 |
| 2007 | 3.1°C | -0.4°C | -4.0°C | 12.7°C | -8.9°C | 42 mm | 75% | 2.4 m/s | 1.3 |
| 2006 | 3.9°C | 0.0°C | -4.0°C | 11.2°C | -9.0°C | 54 mm | 73% | 2 m/s | 1.6 |
| 2005 | 2.6°C | -1.1°C | -4.8°C | 10.9°C | -12.8°C | 105 mm | 81% | 2.2 m/s | 1.3 |
| 2004 | 6.4°C | 2.1°C | -2.3°C | 14.0°C | -7.1°C | 30 mm | 76% | 2 m/s | 1.4 |
| 2003 | 6.6°C | 2.4°C | -1.7°C | 14.9°C | -10.0°C | 64 mm | 73% | 2.6 m/s | 1.3 |
| 2002 | 6.9°C | 2.9°C | -1.2°C | 14.3°C | -5.3°C | 58 mm | 73% | 2.5 m/s | 1.3 |
| 2001 | 3.8°C | 0.0°C | -3.8°C | 7.9°C | -10.2°C | 41 mm | 78% | 2.5 m/s | 1.3 |
| 2000 | 3.5°C | -0.1°C | -3.7°C | 7.4°C | -6.4°C | 23 mm | 78% | 1.7 m/s | 1.4 |
| 1999 | 4.0°C | 0.2°C | -3.6°C | 9.5°C | -9.5°C | 31 mm | 75% | 2 m/s | 1.4 |
| 1998 | 2.5°C | -1.0°C | -4.4°C | 12.5°C | -16.6°C | 44 mm | 72% | 2.4 m/s | 1.3 |
| 1997 | 3.7°C | -0.3°C | -4.3°C | 8.6°C | -9.7°C | 21 mm | 74% | 2 m/s | 1.6 |
| 1996 🌧️ | 4.5°C | 1.2°C | -2.0°C | 11.5°C | -9.8°C | 123 mm | 78% | 3.1 m/s | 1.3 |
| 1995 | 4.9°C | 0.7°C | -3.4°C | 15.3°C | -8.8°C | 70 mm | 79% | 2.2 m/s | 1.3 |
| 1994 | 2.6°C | -1.3°C | -5.2°C | 6.3°C | -13.0°C | 43 mm | 81% | 2.2 m/s | 1.4 |
| 1993 | 3.8°C | -0.1°C | -3.9°C | 9.4°C | -8.3°C | 20 mm | 74% | 2.3 m/s | 1.4 |
| 1992 | 2.0°C | -2.0°C | -6.1°C | 6.4°C | -14.4°C | 43 mm | 80% | 2.8 m/s | 1.3 |
| 1991 | 5.4°C | 1.0°C | -3.3°C | 12.4°C | -6.5°C | 18 mm | 74% | 2.1 m/s | 1.5 |
| 1990 | 0.5°C | -4.4°C | -9.2°C | 12.6°C | -23.7°C | 21 mm | 64% | 2.4 m/s | 1.6 |
| 1989 | 5.5°C | 1.1°C | -3.3°C | 11.4°C | -8.1°C | 4 mm | 71% | 1.6 m/s | 1.6 |
| 1988 | 1.7°C | -2.2°C | -6.0°C | 7.5°C | -15.5°C | 32 mm | 80% | 2 m/s | 1.4 |
| 1987 | 4.4°C | 0.3°C | -3.9°C | 14.3°C | -12.4°C | 34 mm | 71% | 2.8 m/s | 1.4 |
| 1986 | 4.3°C | 0.2°C | -4.0°C | 8.4°C | -7.8°C | 10 mm | 72% | 1.5 m/s | 1.3 |
| 1985 ❄️ | -1.7°C | -5.2°C | -8.8°C | 4.6°C | -15.4°C | 30 mm | 90% | 1.4 m/s | 1.7 |
| 1984 | 1.5°C | -2.9°C | -7.3°C | 6.1°C | -12.1°C | 25 mm | 79% | 2.2 m/s | 1.6 |
| 1983 | -1.1°C | -4.3°C | -7.5°C | 6.6°C | -18.7°C | 97 mm | 88% | 2.2 m/s | — |
| 1982 | 2.4°C | -1.3°C | -4.9°C | 8.9°C | -13.1°C | 69 mm | 83% | 2.6 m/s | — |
| 1981 | 5.4°C | 1.5°C | -2.3°C | 14.5°C | -11.3°C | 95 mm | 80% | 2.6 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 3.8°C with lows near -4.1°C (mean -0.1°C), based on 45 years of NASA POWER data.
December averages 49 mm of rainfall in Nampa, a relatively wet time of year. The wettest on record was 123 mm in 1996.
The hottest December reached 17.2°C in 2021. The coldest dipped to -23.7°C in 1990.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 4.5°C. Daytime highs moved from 1.3°C to 6.2°C and overnight lows from -6.2°C to -2°C over the same span.
December is one of the cooler months of the year in Nampa and a relatively wet time of year, so plan for around 3.8°C daytime highs and -4.1°C at night.
Not quite — December is the 2nd coolest month in Nampa, averaging -0.1°C.
For December in Nampa, pack warm layers and a jacket for chilly mornings, with typical highs of 3.8°C and lows of -4.1°C.
Relative humidity in December averages 76% — quite humid.
Average wind speed in December is 2.2 m/s. The windiest December on record averaged 3.1 m/s (1996).
The wettest December on record was 1996 with 123 mm. On average, December sees 49 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 December, 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 December specifically, along with year-by-year records and how the month has changed over the decades.
