January is one of the cooler months of the year in Simi Valley, with average highs near 15.3°C and lows around 3.2°C (mean 9.3°C). It is a relatively wet time of year, averaging 80 mm of rainfall and 64% relative humidity across the period.
January is one of the cooler months of the year in Simi Valley. Across 45 years of records, the warmest January in Simi Valley was 2014 — when the month averaged 13.6°C — while the coldest was 1989 at 6.7°C. Typical January days reach 15.3°C with nights near 3.2°C. The long-term trend is warming, about 0.4°C per decade.
January is a relatively wet time of year in Simi Valley, averaging 80 mm of rainfall. The wettest January on record was 1995 with 397 mm, while the driest was 2003 at 0 mm.
Relative humidity in Simi Valley during January averages 64%. The most humid January was 1995 at 84%, and the least humid was 2014 at 37%.
January receives about 3.1 kWh/m²/day of solar energy in Simi Valley. The sunniest January was 2025 at 3.5 kWh/m²/day, and the cloudiest was 1995 at 2.4.
Average wind speed in Simi Valley during January is 2.6 m/s. The windiest January was 2006 at 3.3 m/s, while the calmest was 2015 at 2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 8.5°C | 8.8°C | 9.2°C | 10.2°C | 9.5°C | +1°C |
| Avg High | 14.6°C | 14.7°C | 15.2°C | 16.3°C | 15.5°C | +0.9°C |
| Avg Low | 2.3°C | 2.9°C | 3.3°C | 4.1°C | 3.4°C | +1.1°C |
| Avg Rain | 59 mm | 116 mm | 76 mm | 78 mm | 60 mm | +1 mm |
January temperatures in Simi Valley have risen by about 0.8°C between 1981–1985 and 2021–2025.
January has ranged from a record low of -5.1°C (1987) to a record high of 26.9°C (2003).
Rainfall in January is a relatively wet time of year, averaging 80 mm, with a wettest year of 397 mm.
A quieter season to visit Simi Valley
If your dates are flexible, the more temperate months of June and September tend to be the most comfortable for visiting Simi Valley. That said, January — with days averaging 15.3°C and nights around 3.2°C (mean 9.3°C) and moderate rainfall (80 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 | 16.9°C | 9.9°C | 2.9°C | 23.5°C | -0.9°C | 21 mm | 47% | 2.5 m/s | 3.5 |
| 2024 | 15.3°C | 9.7°C | 4.1°C | 22.4°C | -2.2°C | 44 mm | 74% | 2.4 m/s | 3.1 |
| 2023 | 12.2°C | 7.4°C | 2.5°C | 19.2°C | -1.6°C | 237 mm | 78% | 2.5 m/s | 2.8 |
| 2022 | 16.2°C | 9.8°C | 3.4°C | 21.9°C | -1.7°C | 5 mm | 63% | 2.5 m/s | 3.3 |
| 2021 | 16.2°C | 10.2°C | 4.1°C | 24.7°C | -2.2°C | 45 mm | 59% | 2.8 m/s | 3.2 |
| 2020 | 16.3°C | 10.0°C | 3.6°C | 21.5°C | -1.2°C | 10 mm | 71% | 2.7 m/s | 3.4 |
| 2019 | 15.0°C | 9.8°C | 4.6°C | 22.1°C | -2.8°C | 176 mm | 73% | 2.4 m/s | 2.9 |
| 2018 | 19.3°C | 12.8°C | 6.2°C | 25.8°C | -1.3°C | 63 mm | 56% | 2.3 m/s | 3.2 |
| 2017 | 13.0°C | 7.9°C | 2.9°C | 20.5°C | -1.8°C | 196 mm | 77% | 2.3 m/s | 2.9 |
| 2016 | 14.9°C | 9.1°C | 3.4°C | 21.1°C | -1.5°C | 97 mm | 72% | 2.2 m/s | 2.8 |
| 2015 | 17.6°C | 11.5°C | 5.4°C | 22.6°C | -2.9°C | 34 mm | 60% | 2 m/s | 3.2 |
| 2014 🔥 | 20.6°C | 13.6°C | 6.5°C | 24.5°C | 3.4°C | 2 mm | 37% | 2.7 m/s | 3.3 |
| 2013 | 14.3°C | 7.8°C | 1.3°C | 21.2°C | -4.2°C | 30 mm | 57% | 2.6 m/s | 3.3 |
| 2012 | 18.4°C | 11.1°C | 3.8°C | 25.1°C | -3.4°C | 25 mm | 48% | 2.7 m/s | 3.4 |
| 2011 | 15.0°C | 8.9°C | 2.8°C | 21.1°C | -2.5°C | 17 mm | 64% | 2.7 m/s | 3.3 |
| 2010 | 14.9°C | 9.4°C | 3.8°C | 20.5°C | -0.5°C | 136 mm | 66% | 2.4 m/s | 2.8 |
| 2009 | 17.6°C | 10.9°C | 4.2°C | 24.3°C | -1.5°C | 18 mm | 54% | 2.6 m/s | 3.4 |
| 2008 | 12.3°C | 7.2°C | 2.2°C | 19.8°C | -2.8°C | 208 mm | 71% | 3.2 m/s | 2.9 |
| 2007 | 14.1°C | 7.7°C | 1.4°C | 22.0°C | -4.5°C | 32 mm | 52% | 2.5 m/s | 3.4 |
| 2006 | 14.8°C | 9.0°C | 3.1°C | 20.6°C | -1.4°C | 56 mm | 65% | 3.3 m/s | 3.4 |
| 2005 | 13.7°C | 9.1°C | 4.5°C | 21.9°C | 0.0°C | 261 mm | 78% | 2.4 m/s | 2.8 |
| 2004 | 15.7°C | 9.2°C | 2.7°C | 21.1°C | -2.6°C | 15 mm | 60% | 2.3 m/s | 3.3 |
| 2003 | 19.6°C | 13.0°C | 6.4°C | 26.9°C | 1.8°C | 0 mm | 60% | 2.6 m/s | 3.3 |
| 2002 | 14.8°C | 8.1°C | 1.5°C | 23.7°C | -4.4°C | 19 mm | 58% | 2.2 m/s | 3.3 |
| 2001 | 13.5°C | 7.6°C | 1.8°C | 23.2°C | -3.0°C | 112 mm | 62% | 2.3 m/s | 3.1 |
| 2000 | 16.3°C | 10.5°C | 4.8°C | 23.9°C | 0.3°C | 37 mm | 66% | 2.5 m/s | 2.8 |
| 1999 | 16.5°C | 10.0°C | 3.5°C | 23.1°C | -1.9°C | 61 mm | 59% | 2.4 m/s | 3.2 |
| 1998 | 14.8°C | 9.2°C | 3.6°C | 21.6°C | -0.5°C | 80 mm | 77% | 2.1 m/s | 2.9 |
| 1997 | 13.7°C | 8.6°C | 3.6°C | 21.2°C | -1.2°C | 118 mm | 77% | 2.5 m/s | 2.7 |
| 1996 | 16.5°C | 10.1°C | 3.7°C | 22.8°C | -2.5°C | 55 mm | 64% | 2.7 m/s | 2.9 |
| 1995 🌧️ | 12.1°C | 8.1°C | 4.1°C | 20.3°C | -0.3°C | 397 mm | 84% | 2.5 m/s | 2.4 |
| 1994 | 16.8°C | 9.9°C | 3.1°C | 23.1°C | -1.8°C | 18 mm | 51% | 2.6 m/s | 3.4 |
| 1993 | 11.7°C | 7.1°C | 2.5°C | 18.7°C | -3.4°C | 277 mm | 79% | 2.9 m/s | 2.6 |
| 1992 | 14.4°C | 8.0°C | 1.6°C | 19.9°C | -2.0°C | 61 mm | 61% | 3 m/s | 3.1 |
| 1991 | 15.2°C | 8.4°C | 1.6°C | 20.9°C | -1.8°C | 33 mm | 59% | 2.4 m/s | 3.2 |
| 1990 | 15.1°C | 8.6°C | 2.0°C | 24.9°C | -2.6°C | 57 mm | 60% | 2.8 m/s | 3.2 |
| 1989 ❄️ | 12.9°C | 6.7°C | 0.5°C | 19.7°C | -3.4°C | 14 mm | 62% | 3.2 m/s | 3.3 |
| 1988 | 13.6°C | 7.6°C | 1.6°C | 21.3°C | -2.2°C | 71 mm | 67% | 3.1 m/s | 2.9 |
| 1987 | 13.7°C | 7.3°C | 1.0°C | 23.9°C | -5.1°C | 40 mm | 60% | 3 m/s | 3 |
| 1986 | 17.4°C | 11.4°C | 5.3°C | 23.1°C | 2.5°C | 82 mm | 64% | 2.8 m/s | 3 |
| 1985 | 13.2°C | 7.2°C | 1.1°C | 21.4°C | -4.0°C | 24 mm | 65% | 2.7 m/s | 3.2 |
| 1984 | 16.1°C | 9.6°C | 3.1°C | 22.3°C | -2.1°C | 3 mm | 59% | 3 m/s | 3.4 |
| 1983 | 14.8°C | 9.0°C | 3.2°C | 20.8°C | -2.8°C | 164 mm | 67% | 2.9 m/s | — |
| 1982 | 13.1°C | 6.9°C | 0.8°C | 21.4°C | -3.3°C | 67 mm | 64% | 3.1 m/s | — |
| 1981 | 16.4°C | 10.4°C | 4.5°C | 22.2°C | -1.6°C | 68 mm | 57% | 2.5 m/s | — |
Actual recorded January data for each year, 1981–2025 — sourced from NASA POWER.
The average high in January is around 15.3°C with lows near 3.2°C (mean 9.3°C), based on 45 years of NASA POWER data.
January averages 80 mm of rainfall in Simi Valley, a relatively wet time of year. The wettest on record was 397 mm in 1995.
The hottest January reached 26.9°C in 2003. The coldest dipped to -5.1°C in 1987.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average January temperatures have risen by about 0.8°C. Daytime highs moved from 14.7°C to 15.4°C and overnight lows from 2.5°C to 3.4°C over the same span.
January is one of the cooler months of the year in Simi Valley and a relatively wet time of year, so plan for around 15.3°C daytime highs and 3.2°C at night.
Not quite — January is the 2nd coolest month in Simi Valley, averaging 9.3°C.
For January in Simi Valley, pack warm layers and a jacket for chilly mornings, with typical highs of 15.3°C and lows of 3.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in January averages 64% — moderately humid.
Average wind speed in January is 2.6 m/s. The windiest January on record averaged 3.3 m/s (2006).
The wettest January on record was 1995 with 397 mm. On average, January sees 80 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 Simi Valley behaves each January, 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 January specifically, along with year-by-year records and how the month has changed over the decades.
