December is one of the cooler months of the year in Twin Falls, with average highs near 2.6°C and lows around -6.1°C (mean -1.7°C). It is a relatively wet time of year, averaging 45 mm of rainfall and 77% relative humidity across the period.
December is one of the cooler months of the year in Twin Falls. Across 45 years of records, the warmest December in Twin Falls was 2025 — when the month averaged 4.1°C — while the coldest was 1983 at -6.5°C. Typical December days reach 2.6°C with nights near -6.1°C. The long-term trend is warming, about 0.7°C per decade.
December is a relatively wet time of year in Twin Falls, averaging 45 mm of rainfall. The wettest December on record was 1996 with 107 mm, while the driest was 1989 at 3 mm.
Relative humidity in Twin Falls during December averages 77%. The most humid December was 1983 at 91%, and the least humid was 2013 at 67%.
December receives about 1.6 kWh/m²/day of solar energy in Twin Falls. The sunniest December was 2011 at 2.1 kWh/m²/day, and the cloudiest was 2015 at 1.2.
Average wind speed in Twin Falls during December is 2.9 m/s. The windiest December was 1996 at 3.7 m/s, while the calmest was 1985 at 1.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | -2.8°C | -2.1°C | -1.6°C | -1.9°C | 0.7°C | +3.5°C |
| Avg High | 1.6°C | 2.2°C | 2.6°C | 2.4°C | 5.1°C | +3.5°C |
| Avg Low | -7.2°C | -6.4°C | -5.9°C | -6.2°C | -3.7°C | +3.5°C |
| Avg Rain | 34 mm | 34 mm | 53 mm | 55 mm | 47 mm | +13 mm |
December temperatures in Twin Falls have risen by about 4.8°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -24.2°C (1990) to a record high of 16.1°C (2025).
Rainfall in December is a relatively wet time of year, averaging 45 mm, with a wettest year of 107 mm.
A quieter season to visit Twin Falls
If your dates are flexible, the more temperate months of August and July tend to be the most comfortable for visiting Twin Falls. That said, December — with days averaging 2.6°C and nights around -6.1°C (mean -1.7°C) and moderate rainfall (45 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 🔥 | 9.0°C | 4.1°C | -0.8°C | 16.1°C | -5.7°C | 62 mm | 68% | 3.3 m/s | — |
| 2024 | 6.1°C | 2.1°C | -2.0°C | 11.5°C | -6.2°C | 72 mm | 73% | 2.6 m/s | 1.7 |
| 2023 | 5.0°C | 1.0°C | -3.0°C | 14.2°C | -6.8°C | 40 mm | 80% | 2.5 m/s | 1.6 |
| 2022 | 2.1°C | -2.1°C | -6.3°C | 9.1°C | -15.7°C | 46 mm | 78% | 2.8 m/s | 1.6 |
| 2021 | 4.8°C | 0.1°C | -4.5°C | 14.5°C | -17.3°C | 46 mm | 71% | 3.4 m/s | 1.4 |
| 2020 | 3.7°C | -1.0°C | -5.8°C | 12.6°C | -10.0°C | 18 mm | 68% | 2.8 m/s | 1.9 |
| 2019 | 3.1°C | -0.9°C | -4.9°C | 8.0°C | -12.2°C | 47 mm | 80% | 2.6 m/s | 1.3 |
| 2018 | 1.5°C | -2.8°C | -7.1°C | 8.2°C | -14.1°C | 39 mm | 81% | 2.9 m/s | 1.5 |
| 2017 | 2.5°C | -1.8°C | -6.1°C | 8.2°C | -13.0°C | 32 mm | 73% | 2.7 m/s | 1.6 |
| 2016 | -0.7°C | -5.1°C | -9.4°C | 7.1°C | -18.0°C | 84 mm | 85% | 3.2 m/s | 1.5 |
| 2015 | 1.4°C | -2.9°C | -7.3°C | 13.2°C | -20.5°C | 85 mm | 83% | 3.2 m/s | 1.2 |
| 2014 | 5.6°C | 1.1°C | -3.4°C | 14.2°C | -18.2°C | 63 mm | 77% | 3.1 m/s | 1.5 |
| 2013 | 2.0°C | -2.4°C | -6.8°C | 10.3°C | -15.8°C | 12 mm | 67% | 3.1 m/s | 1.6 |
| 2012 | 2.7°C | -1.6°C | -5.8°C | 13.4°C | -15.2°C | 84 mm | 77% | 3.4 m/s | 1.4 |
| 2011 | 3.2°C | -1.6°C | -6.3°C | 11.9°C | -12.3°C | 16 mm | 68% | 2.6 m/s | 2.1 |
| 2010 | 2.7°C | -1.2°C | -5.0°C | 10.3°C | -18.5°C | 88 mm | 85% | 2.9 m/s | 1.3 |
| 2009 | 0.0°C | -4.3°C | -8.6°C | 6.9°C | -16.0°C | 40 mm | 76% | 2.6 m/s | 1.6 |
| 2008 | 1.9°C | -2.7°C | -7.3°C | 13.9°C | -16.0°C | 73 mm | 76% | 3.2 m/s | 1.5 |
| 2007 | 1.5°C | -2.6°C | -6.7°C | 9.3°C | -15.4°C | 41 mm | 78% | 3 m/s | 1.3 |
| 2006 | 3.1°C | -1.3°C | -5.7°C | 12.6°C | -11.9°C | 57 mm | 73% | 2.6 m/s | 1.7 |
| 2005 | 1.7°C | -2.4°C | -6.5°C | 11.9°C | -16.9°C | 94 mm | 81% | 2.9 m/s | 1.5 |
| 2004 | 4.6°C | 0.2°C | -4.2°C | 12.3°C | -12.2°C | 47 mm | 78% | 2.7 m/s | 1.5 |
| 2003 | 4.7°C | 0.5°C | -3.6°C | 11.6°C | -9.1°C | 64 mm | 77% | 3.2 m/s | 1.4 |
| 2002 | 5.5°C | 1.3°C | -2.9°C | 13.6°C | -8.9°C | 35 mm | 73% | 2.6 m/s | 1.4 |
| 2001 | 0.4°C | -4.0°C | -8.5°C | 3.6°C | -14.1°C | 59 mm | 87% | 2.8 m/s | 1.4 |
| 2000 | 3.1°C | -1.2°C | -5.4°C | 7.7°C | -10.1°C | 19 mm | 76% | 2.4 m/s | 1.6 |
| 1999 | 3.5°C | -0.7°C | -4.9°C | 7.9°C | -8.4°C | 17 mm | 72% | 2.8 m/s | 1.7 |
| 1998 | 1.7°C | -2.4°C | -6.4°C | 10.6°C | -17.8°C | 23 mm | 71% | 3 m/s | 1.5 |
| 1997 | 2.2°C | -2.1°C | -6.4°C | 7.0°C | -11.5°C | 14 mm | 75% | 2.7 m/s | 1.6 |
| 1996 🌧️ | 2.4°C | -1.2°C | -4.8°C | 7.7°C | -14.1°C | 107 mm | 81% | 3.7 m/s | 1.3 |
| 1995 | 4.1°C | -0.2°C | -4.6°C | 14.6°C | -10.8°C | 65 mm | 78% | 2.7 m/s | 1.4 |
| 1994 | 3.0°C | -1.3°C | -5.6°C | 9.4°C | -13.4°C | 23 mm | 79% | 2.4 m/s | 1.5 |
| 1993 | 3.5°C | -0.9°C | -5.4°C | 12.0°C | -9.7°C | 12 mm | 72% | 3 m/s | 1.6 |
| 1992 | -0.1°C | -4.7°C | -9.3°C | 4.2°C | -15.8°C | 47 mm | 83% | 3.2 m/s | 1.5 |
| 1991 | 3.2°C | -1.5°C | -6.3°C | 8.5°C | -11.4°C | 9 mm | 77% | 2.8 m/s | 1.7 |
| 1990 | -1.5°C | -6.1°C | -10.8°C | 11.8°C | -24.2°C | 21 mm | 68% | 3 m/s | 1.7 |
| 1989 | 4.1°C | -0.3°C | -4.8°C | 9.7°C | -9.9°C | 3 mm | 71% | 2.7 m/s | 1.8 |
| 1988 | 0.7°C | -3.6°C | -8.0°C | 7.2°C | -17.2°C | 21 mm | 80% | 2.9 m/s | 1.7 |
| 1987 | 2.6°C | -2.1°C | -6.8°C | 13.9°C | -16.0°C | 31 mm | 75% | 3.1 m/s | 1.5 |
| 1986 | 4.1°C | -0.6°C | -5.3°C | 8.3°C | -8.7°C | 3 mm | 69% | 1.8 m/s | 1.6 |
| 1985 | -1.3°C | -5.7°C | -10.1°C | 4.7°C | -22.5°C | 25 mm | 90% | 1.7 m/s | 1.8 |
| 1984 | 1.1°C | -4.0°C | -9.0°C | 7.5°C | -14.7°C | 18 mm | 79% | 3.1 m/s | 1.8 |
| 1983 ❄️ | -2.6°C | -6.5°C | -10.3°C | 4.2°C | -21.4°C | 81 mm | 91% | 3 m/s | — |
| 1982 | 1.4°C | -2.5°C | -6.4°C | 8.3°C | -16.4°C | 38 mm | 82% | 3 m/s | — |
| 1981 | 4.3°C | -0.1°C | -4.5°C | 14.7°C | -16.0°C | 86 mm | 82% | 3.4 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 2.6°C with lows near -6.1°C (mean -1.7°C), based on 45 years of NASA POWER data.
December averages 45 mm of rainfall in Twin Falls, a relatively wet time of year. The wettest on record was 107 mm in 1996.
The hottest December reached 16.1°C in 2025. The coldest dipped to -24.2°C in 1990.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 4.8°C. Daytime highs moved from 0.6°C to 5.4°C and overnight lows from -8.1°C to -3.3°C over the same span.
December is one of the cooler months of the year in Twin Falls and a relatively wet time of year, so plan for around 2.6°C daytime highs and -6.1°C at night.
Not quite — December is the 2nd coolest month in Twin Falls, averaging -1.7°C.
For December in Twin Falls, pack warm layers and a jacket for chilly mornings, with typical highs of 2.6°C and lows of -6.1°C.
Relative humidity in December averages 77% — quite humid.
Average wind speed in December is 2.9 m/s. The windiest December on record averaged 3.7 m/s (1996).
The wettest December on record was 1996 with 107 mm. On average, December sees 45 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 Twin Falls 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.
