December is one of the cooler months of the year in Pasadena, with average highs near 17.7°C and lows around 9.9°C (mean 13.8°C). It is about average for rainfall, averaging 110 mm of rainfall and 82% relative humidity across the period.
December is one of the cooler months of the year in Pasadena. Across 45 years of records, the warmest December in Pasadena was 2021 — when the month averaged 19.3°C — while the coldest was 1989 at 9°C. Typical December days reach 17.7°C with nights near 9.9°C. The long-term trend is warming, about 0.5°C per decade.
December is about average for rainfall in Pasadena, averaging 110 mm of rainfall. The wettest December on record was 2016 with 280 mm, while the driest was 2013 at 24 mm.
Relative humidity in Pasadena during December averages 82%. The most humid December was 1984 at 90%, and the least humid was 1989 at 75%.
December receives about 2.6 kWh/m²/day of solar energy in Pasadena. The sunniest December was 2003 at 3.3 kWh/m²/day, and the cloudiest was 1992 at 2.
Average wind speed in Pasadena during December is 3.6 m/s. The windiest December was 1983 at 4.1 m/s, while the calmest was 2025 at 3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.9°C | 14.0°C | 12.9°C | 14.1°C | 15.7°C | +2.8°C |
| Avg High | 16.7°C | 17.8°C | 16.8°C | 18.1°C | 19.8°C | +3.1°C |
| Avg Low | 9.1°C | 10.3°C | 8.9°C | 10.2°C | 11.6°C | +2.5°C |
| Avg Rain | 101 mm | 126 mm | 98 mm | 121 mm | 97 mm | -4 mm |
December temperatures in Pasadena have risen by about 2.9°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -7.3°C (1989) to a record high of 26°C (2021).
Rainfall in December is about average for rainfall, averaging 110 mm, with a wettest year of 280 mm.
A quieter season to visit Pasadena
If your dates are flexible, the more temperate months of April and October tend to be the most comfortable for visiting Pasadena. That said, December — with days averaging 17.7°C and nights around 9.9°C (mean 13.8°C) and higher rainfall (110 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 | 19.9°C | 15.6°C | 11.3°C | 25.7°C | 1.8°C | 68 mm | 82% | 3 m/s | — |
| 2024 | 20.6°C | 16.5°C | 12.5°C | 24.4°C | 5.4°C | 128 mm | 82% | 3.4 m/s | 2.8 |
| 2023 | 18.7°C | 14.6°C | 10.5°C | 25.1°C | 3.1°C | 87 mm | 80% | 3.2 m/s | 3.1 |
| 2022 | 18.5°C | 14.5°C | 10.4°C | 25.2°C | -6.2°C | 115 mm | 84% | 3.1 m/s | 2.6 |
| 2021 🔥 | 22.8°C | 19.3°C | 15.8°C | 26.0°C | 6.6°C | 43 mm | 87% | 3.2 m/s | 2.6 |
| 2020 | 18.1°C | 13.6°C | 9.1°C | 22.4°C | 2.1°C | 142 mm | 82% | 3.6 m/s | 2.8 |
| 2019 | 18.8°C | 14.3°C | 9.8°C | 24.7°C | 2.8°C | 38 mm | 78% | 3.2 m/s | 3.1 |
| 2018 | 17.4°C | 13.6°C | 9.9°C | 22.9°C | 5.2°C | 182 mm | 84% | 3.8 m/s | 2.7 |
| 2017 | 16.7°C | 12.8°C | 8.9°C | 24.6°C | 1.3°C | 166 mm | 82% | 3.3 m/s | 2.3 |
| 2016 🌧️ | 19.0°C | 15.5°C | 11.9°C | 24.7°C | 1.0°C | 280 mm | 85% | 3.6 m/s | 2.3 |
| 2015 | 19.6°C | 15.8°C | 12.1°C | 25.2°C | 5.3°C | 104 mm | 85% | 3.7 m/s | 2.7 |
| 2014 | 18.3°C | 14.6°C | 10.9°C | 23.9°C | 4.8°C | 116 mm | 86% | 3.2 m/s | 2.1 |
| 2013 | 15.6°C | 11.7°C | 7.8°C | 23.7°C | 1.6°C | 24 mm | 82% | 3.2 m/s | 2.4 |
| 2012 | 20.4°C | 15.9°C | 11.4°C | 25.4°C | 1.8°C | 96 mm | 79% | 3.5 m/s | 2.7 |
| 2011 | 17.2°C | 13.6°C | 10.1°C | 23.3°C | 0.0°C | 124 mm | 84% | 3.6 m/s | 2.3 |
| 2010 | 17.8°C | 13.6°C | 9.4°C | 24.4°C | 0.3°C | 81 mm | 76% | 3.7 m/s | 2.8 |
| 2009 | 14.6°C | 10.9°C | 7.1°C | 22.8°C | -0.6°C | 165 mm | 84% | 3.7 m/s | 2.2 |
| 2008 | 17.7°C | 13.6°C | 9.5°C | 23.4°C | 1.1°C | 45 mm | 80% | 4 m/s | 2.4 |
| 2007 | 19.4°C | 14.9°C | 10.4°C | 24.7°C | 0.9°C | 52 mm | 82% | 3.4 m/s | 3.1 |
| 2006 | 16.8°C | 13.2°C | 9.6°C | 22.2°C | 1.1°C | 95 mm | 82% | 3.6 m/s | 2.6 |
| 2005 | 17.0°C | 12.8°C | 8.5°C | 25.7°C | 3.1°C | 70 mm | 76% | 3.5 m/s | 2.9 |
| 2004 | 16.7°C | 12.8°C | 9.0°C | 23.4°C | 0.4°C | 58 mm | 82% | 3.5 m/s | 2.9 |
| 2003 | 17.4°C | 12.9°C | 8.4°C | 22.4°C | 2.1°C | 111 mm | 78% | 3.9 m/s | 3.3 |
| 2002 | 16.6°C | 13.0°C | 9.4°C | 21.6°C | 1.9°C | 190 mm | 86% | 3.9 m/s | 2.5 |
| 2001 | 18.1°C | 14.5°C | 10.8°C | 23.9°C | 3.7°C | 125 mm | 83% | 3.5 m/s | 2.7 |
| 2000 | 14.1°C | 10.0°C | 5.9°C | 22.5°C | 0.1°C | 68 mm | 82% | 3.9 m/s | 2.6 |
| 1999 | 18.4°C | 13.7°C | 8.9°C | 24.3°C | 3.1°C | 104 mm | 76% | 3.8 m/s | 3.2 |
| 1998 | 17.6°C | 14.2°C | 10.7°C | 25.4°C | 0.2°C | 109 mm | 86% | 3.7 m/s | 2.6 |
| 1997 | 16.0°C | 11.7°C | 7.5°C | 22.5°C | 0.7°C | 124 mm | 81% | 3.7 m/s | 3 |
| 1996 | 18.5°C | 14.5°C | 10.6°C | 24.2°C | -2.6°C | 83 mm | 83% | 3.5 m/s | 2.7 |
| 1995 | 17.3°C | 13.7°C | 10.1°C | 25.7°C | 0.5°C | 175 mm | 83% | 3.5 m/s | 2.7 |
| 1994 | 18.2°C | 14.8°C | 11.4°C | 24.9°C | 3.7°C | 199 mm | 86% | 3.3 m/s | 2.4 |
| 1993 | 16.9°C | 13.3°C | 9.8°C | 23.8°C | 1.5°C | 73 mm | 81% | 3.8 m/s | 2.3 |
| 1992 | 18.1°C | 14.7°C | 11.2°C | 23.3°C | 6.1°C | 125 mm | 86% | 3.3 m/s | 2 |
| 1991 | 17.8°C | 15.0°C | 12.2°C | 23.5°C | 3.7°C | 185 mm | 86% | 3.8 m/s | 2.1 |
| 1990 | 18.7°C | 14.5°C | 10.4°C | 24.5°C | -3.6°C | 80 mm | 79% | 3.7 m/s | 2.4 |
| 1989 ❄️ | 13.3°C | 9.0°C | 4.6°C | 23.6°C | -7.3°C | 25 mm | 75% | 3.6 m/s | 2.5 |
| 1988 | 19.4°C | 15.1°C | 10.9°C | 24.3°C | 3.9°C | 78 mm | 76% | 3.5 m/s | 2.5 |
| 1987 | 18.1°C | 14.3°C | 10.4°C | 23.8°C | 1.0°C | 119 mm | 84% | 3.6 m/s | 2.2 |
| 1986 | 15.0°C | 12.0°C | 8.9°C | 22.6°C | 3.3°C | 169 mm | 86% | 3.3 m/s | 2.2 |
| 1985 | 15.7°C | 11.5°C | 7.4°C | 22.3°C | -2.8°C | 79 mm | 82% | 3.3 m/s | 2.8 |
| 1984 | 20.0°C | 17.0°C | 14.0°C | 23.7°C | 0.6°C | 84 mm | 90% | 3.7 m/s | 2.4 |
| 1983 | 13.7°C | 9.6°C | 5.5°C | 24.4°C | -6.6°C | 92 mm | 82% | 4.1 m/s | — |
| 1982 | 18.1°C | 14.5°C | 10.9°C | 24.2°C | 1.7°C | 183 mm | 84% | 4 m/s | — |
| 1981 | 17.3°C | 13.5°C | 9.6°C | 23.3°C | 1.0°C | 83 mm | 80% | 3.7 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 17.7°C with lows near 9.9°C (mean 13.8°C), based on 45 years of NASA POWER data.
December averages 110 mm of rainfall in Pasadena, about average for rainfall. The wettest on record was 280 mm in 2016.
The hottest December reached 26°C in 2021. The coldest dipped to -7.3°C in 1989.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 2.9°C. Daytime highs moved from 17°C to 20.1°C and overnight lows from 9.5°C to 12.1°C over the same span.
December is one of the cooler months of the year in Pasadena and about average for rainfall, so plan for around 17.7°C daytime highs and 9.9°C at night.
Not quite — December is the 3rd coolest month in Pasadena, averaging 13.8°C.
For December in Pasadena, pack light layers you can adjust through the day, with typical highs of 17.7°C and lows of 9.9°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 82% — quite humid.
Average wind speed in December is 3.6 m/s. The windiest December on record averaged 4.1 m/s (1983).
The wettest December on record was 2016 with 280 mm. On average, December sees 110 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 Pasadena 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.
