December is one of the cooler months of the year in Pasadena, with average highs near 17.8°C and lows around 7.6°C (mean 12.7°C). It is a relatively wet time of year, averaging 64 mm of rainfall and 58% 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 2017 — when the month averaged 16.4°C — while the coldest was 1987 at 9.6°C. Typical December days reach 17.8°C with nights near 7.6°C. The long-term trend is warming, about 0.5°C per decade.
December is a relatively wet time of year in Pasadena, averaging 64 mm of rainfall. The wettest December on record was 2010 with 262 mm, while the driest was 2017 at 0 mm.
Relative humidity in Pasadena during December averages 58%. The most humid December was 1983 at 71%, and the least humid was 2017 at 34%.
December receives about 2.8 kWh/m²/day of solar energy in Pasadena. The sunniest December was 2017 at 3.3 kWh/m²/day, and the cloudiest was 1987 at 2.4.
Average wind speed in Pasadena during December is 2.4 m/s. The windiest December was 1997 at 3.2 m/s, while the calmest was 2024 at 1.6 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.1°C | 12.2°C | 12.5°C | 13.1°C | 14.3°C | +2.2°C |
| Avg High | 17.3°C | 17.4°C | 17.6°C | 18.1°C | 19.3°C | +2°C |
| Avg Low | 6.8°C | 6.9°C | 7.5°C | 8.1°C | 9.4°C | +2.6°C |
| Avg Rain | 55 mm | 53 mm | 48 mm | 79 mm | 98 mm | +43 mm |
December temperatures in Pasadena have risen by about 2.2°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -2.6°C (1990) to a record high of 28.5°C (2025).
Rainfall in December is a relatively wet time of year, averaging 64 mm, with a wettest year of 262 mm.
A quieter season to visit Pasadena
If your dates are flexible, the more temperate months of June and September tend to be the most comfortable for visiting Pasadena. That said, December — with days averaging 17.8°C and nights around 7.6°C (mean 12.7°C) and moderate rainfall (64 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 | 21.2°C | 16.2°C | 11.3°C | 28.5°C | 6.5°C | 157 mm | 64% | 2 m/s | — |
| 2024 | 21.1°C | 15.5°C | 10.0°C | 27.0°C | 6.2°C | 1 mm | 53% | 1.6 m/s | 2.9 |
| 2023 | 20.1°C | 15.1°C | 10.1°C | 26.3°C | 7.0°C | 65 mm | 62% | 1.8 m/s | 2.7 |
| 2022 | 16.9°C | 12.6°C | 8.3°C | 25.6°C | 2.3°C | 97 mm | 69% | 1.8 m/s | 2.5 |
| 2021 | 16.3°C | 12.2°C | 8.0°C | 27.9°C | 3.7°C | 234 mm | 68% | 2.2 m/s | 2.6 |
| 2020 | 20.1°C | 14.4°C | 8.7°C | 26.7°C | 4.7°C | 35 mm | 47% | 2.4 m/s | 3 |
| 2019 | 16.5°C | 12.2°C | 8.0°C | 22.1°C | 3.1°C | 140 mm | 70% | 2.2 m/s | 2.5 |
| 2018 | 18.3°C | 13.4°C | 8.4°C | 23.2°C | 2.7°C | 63 mm | 62% | 2.1 m/s | 2.9 |
| 2017 🔥 | 22.3°C | 16.4°C | 10.4°C | 27.3°C | 3.9°C | 0 mm | 34% | 2.2 m/s | 3.3 |
| 2016 | 17.5°C | 12.7°C | 7.9°C | 23.4°C | 0.9°C | 121 mm | 63% | 2.4 m/s | 2.8 |
| 2015 | 17.8°C | 12.4°C | 6.9°C | 27.6°C | 2.2°C | 23 mm | 53% | 2.5 m/s | 3 |
| 2014 | 18.0°C | 13.6°C | 9.3°C | 24.9°C | 2.3°C | 102 mm | 68% | 2 m/s | 2.6 |
| 2013 | 19.3°C | 13.4°C | 7.6°C | 25.3°C | 0.9°C | 8 mm | 47% | 2.2 m/s | 3.2 |
| 2012 | 16.3°C | 11.8°C | 7.2°C | 22.9°C | 1.9°C | 55 mm | 68% | 2 m/s | 2.7 |
| 2011 | 17.7°C | 12.0°C | 6.4°C | 24.4°C | 2.4°C | 16 mm | 50% | 2.2 m/s | 3.2 |
| 2010 🌧️ | 17.3°C | 12.9°C | 8.5°C | 27.5°C | 1.0°C | 262 mm | 70% | 2.3 m/s | 2.5 |
| 2009 | 16.5°C | 11.7°C | 7.0°C | 24.2°C | 0.5°C | 75 mm | 61% | 2.2 m/s | 2.8 |
| 2008 | 16.3°C | 11.4°C | 6.5°C | 26.4°C | 0.6°C | 75 mm | 64% | 2.3 m/s | 2.8 |
| 2007 | 16.4°C | 11.3°C | 6.3°C | 27.0°C | 1.3°C | 39 mm | 58% | 2.6 m/s | 3 |
| 2006 | 19.0°C | 13.2°C | 7.4°C | 26.1°C | 3.0°C | 20 mm | 48% | 2.5 m/s | 3.1 |
| 2005 | 19.1°C | 13.9°C | 8.8°C | 26.1°C | 4.3°C | 17 mm | 57% | 2 m/s | 2.7 |
| 2004 | 17.7°C | 12.9°C | 8.0°C | 26.4°C | 2.5°C | 132 mm | 62% | 2.7 m/s | 2.9 |
| 2003 | 17.3°C | 12.2°C | 7.1°C | 23.3°C | 1.4°C | 35 mm | 61% | 2.2 m/s | 2.7 |
| 2002 | 16.7°C | 12.0°C | 7.3°C | 21.2°C | 2.6°C | 56 mm | 66% | 2.1 m/s | 2.8 |
| 2001 | 16.6°C | 11.6°C | 6.7°C | 23.6°C | 2.7°C | 27 mm | 61% | 2.3 m/s | 2.7 |
| 2000 | 20.3°C | 14.9°C | 9.5°C | 25.0°C | 5.1°C | 0 mm | 47% | 2 m/s | 2.9 |
| 1999 | 19.8°C | 13.9°C | 8.0°C | 25.4°C | 3.9°C | 7 mm | 41% | 2.8 m/s | 3.1 |
| 1998 | 17.7°C | 12.0°C | 6.3°C | 26.2°C | 0.6°C | 15 mm | 49% | 2.8 m/s | 3 |
| 1997 | 16.8°C | 11.6°C | 6.5°C | 23.7°C | 1.8°C | 88 mm | 57% | 3.2 m/s | 2.9 |
| 1996 | 16.9°C | 12.5°C | 8.0°C | 21.9°C | 4.1°C | 117 mm | 68% | 2.9 m/s | 2.6 |
| 1995 | 19.2°C | 13.8°C | 8.4°C | 25.8°C | 4.1°C | 38 mm | 61% | 2.5 m/s | 2.6 |
| 1994 | 17.0°C | 12.0°C | 6.9°C | 22.8°C | 2.3°C | 27 mm | 62% | 2.3 m/s | 2.8 |
| 1993 | 17.9°C | 12.3°C | 6.7°C | 23.3°C | 2.5°C | 26 mm | 54% | 2.7 m/s | 3 |
| 1992 | 15.2°C | 10.4°C | 5.6°C | 21.9°C | 1.0°C | 131 mm | 64% | 3 m/s | 2.8 |
| 1991 | 17.2°C | 12.4°C | 7.7°C | 21.4°C | 3.1°C | 77 mm | 56% | 2.6 m/s | 2.9 |
| 1990 | 16.7°C | 10.8°C | 4.9°C | 24.3°C | -2.6°C | 2 mm | 43% | 3 m/s | 3 |
| 1989 | 20.5°C | 14.4°C | 8.2°C | 26.9°C | 3.2°C | 1 mm | 39% | 2.6 m/s | 3 |
| 1988 | 16.1°C | 11.1°C | 6.1°C | 26.9°C | -0.6°C | 102 mm | 58% | 2.8 m/s | 2.6 |
| 1987 ❄️ | 14.3°C | 9.6°C | 4.8°C | 24.0°C | -1.0°C | 73 mm | 63% | 3 m/s | 2.4 |
| 1986 | 18.6°C | 13.1°C | 7.7°C | 24.2°C | 4.2°C | 16 mm | 54% | 2.2 m/s | 2.7 |
| 1985 | 18.2°C | 12.9°C | 7.5°C | 23.7°C | 0.8°C | 17 mm | 56% | 2.8 m/s | 2.9 |
| 1984 | 15.0°C | 10.2°C | 5.4°C | 20.2°C | 0.8°C | 142 mm | 69% | 2.9 m/s | 2.5 |
| 1983 | 16.5°C | 11.7°C | 6.9°C | 22.3°C | 1.8°C | 81 mm | 71% | 2.6 m/s | — |
| 1982 | 16.5°C | 11.4°C | 6.2°C | 21.7°C | 1.4°C | 44 mm | 59% | 3.1 m/s | — |
| 1981 | 19.9°C | 14.3°C | 8.7°C | 24.5°C | 4.1°C | 17 mm | 56% | 2.5 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 17.8°C with lows near 7.6°C (mean 12.7°C), based on 45 years of NASA POWER data.
December averages 64 mm of rainfall in Pasadena, a relatively wet time of year. The wettest on record was 262 mm in 2010.
The hottest December reached 28.5°C in 2025. The coldest dipped to -2.6°C in 1990.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 2.2°C. Daytime highs moved from 17.2°C to 19.1°C and overnight lows from 6.9°C to 9.5°C over the same span.
December is one of the cooler months of the year in Pasadena and a relatively wet time of year, so plan for around 17.8°C daytime highs and 7.6°C at night.
Not quite — December is the 2nd coolest month in Pasadena, averaging 12.7°C.
For December in Pasadena, pack warm layers and a jacket for chilly mornings, with typical highs of 17.8°C and lows of 7.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in December averages 58% — moderately humid.
Average wind speed in December is 2.4 m/s. The windiest December on record averaged 3.2 m/s (1997).
The wettest December on record was 2010 with 262 mm. On average, December sees 64 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.
