January is one of the cooler months of the year in San Tan Valley, with average highs near 18.1°C and lows around 4.2°C (mean 11.2°C). It is about average for rainfall, averaging 36 mm of rainfall and 49% relative humidity across the period.
January is one of the cooler months of the year in San Tan Valley. Across 45 years of records, the warmest January in San Tan Valley was 2003 — when the month averaged 15.1°C — while the coldest was 1985 at 8.5°C. Typical January days reach 18.1°C with nights near 4.2°C. The long-term trend is warming, about 0.3°C per decade.
January is about average for rainfall in San Tan Valley, averaging 36 mm of rainfall. The wettest January on record was 1993 with 198 mm, while the driest was 2014 at 0 mm.
Relative humidity in San Tan Valley during January averages 49%. The most humid January was 1993 at 76%, and the least humid was 2006 at 26%.
January receives about 3.4 kWh/m²/day of solar energy in San Tan Valley. The sunniest Januarys were 2006 and 2011 at 3.8 kWh/m²/day, and the cloudiest was 1993 at 2.8.
Average wind speed in San Tan Valley during January is 2.4 m/s. The windiest January was 1992 at 3.4 m/s, while the calmest was 1998 at 1.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 10.7°C | 10.6°C | 11.5°C | 11.8°C | 11.2°C | +0.5°C |
| Avg High | 17.6°C | 17.4°C | 18.4°C | 18.8°C | 18.1°C | +0.5°C |
| Avg Low | 3.7°C | 3.8°C | 4.5°C | 4.8°C | 4.2°C | +0.5°C |
| Avg Rain | 39 mm | 51 mm | 29 mm | 35 mm | 22 mm | -18 mm |
January temperatures in San Tan Valley have risen by about 0.4°C between 1981–1985 and 2021–2025.
January has ranged from a record low of -6.6°C (2007) to a record high of 28.6°C (2003).
Rainfall in January is about average for rainfall, averaging 36 mm, with a wettest year of 198 mm.
A quieter season to visit San Tan Valley
If your dates are flexible, the more temperate months of October and May tend to be the most comfortable for visiting San Tan Valley. That said, January — with days averaging 18.1°C and nights around 4.2°C (mean 11.2°C) and moderate rainfall (36 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 | 18.1°C | 10.7°C | 3.4°C | 27.3°C | -1.1°C | 3 mm | 27% | 2.5 m/s | 3.7 |
| 2024 | 17.0°C | 10.7°C | 4.3°C | 25.9°C | -3.9°C | 34 mm | 51% | 1.9 m/s | 3.1 |
| 2023 | 16.0°C | 9.7°C | 3.5°C | 23.8°C | -3.0°C | 52 mm | 57% | 2.2 m/s | 3.2 |
| 2022 | 19.3°C | 12.0°C | 4.6°C | 23.1°C | -2.6°C | 7 mm | 44% | 2.4 m/s | 3.7 |
| 2021 | 19.3°C | 12.0°C | 4.6°C | 25.9°C | -1.1°C | 24 mm | 38% | 2.5 m/s | 3.4 |
| 2020 | 18.8°C | 11.8°C | 4.7°C | 23.4°C | 0.1°C | 9 mm | 51% | 1.9 m/s | 3.5 |
| 2019 | 18.5°C | 11.5°C | 4.5°C | 24.9°C | -3.7°C | 21 mm | 52% | 2 m/s | 3.3 |
| 2018 | 22.1°C | 14.8°C | 7.5°C | 26.7°C | -0.5°C | 9 mm | 31% | 2.6 m/s | 3.6 |
| 2017 | 16.7°C | 10.8°C | 4.9°C | 25.2°C | -2.0°C | 49 mm | 58% | 2.1 m/s | 2.9 |
| 2016 | 17.8°C | 10.9°C | 4.0°C | 24.4°C | 0.2°C | 45 mm | 50% | 2.4 m/s | 3.4 |
| 2015 | 19.0°C | 12.4°C | 5.9°C | 26.6°C | -3.8°C | 43 mm | 52% | 2.3 m/s | 3.1 |
| 2014 | 21.1°C | 13.5°C | 5.9°C | 24.4°C | 1.0°C | 0 mm | 35% | 2.3 m/s | 3.7 |
| 2013 | 16.4°C | 9.5°C | 2.6°C | 25.8°C | -4.1°C | 36 mm | 46% | 2.4 m/s | 3.5 |
| 2012 | 20.2°C | 12.6°C | 5.0°C | 24.6°C | 0.4°C | 12 mm | 41% | 2.2 m/s | 3.5 |
| 2011 | 18.4°C | 10.8°C | 3.2°C | 24.5°C | -5.1°C | 1 mm | 41% | 2.2 m/s | 3.8 |
| 2010 | 17.3°C | 11.0°C | 4.6°C | 22.0°C | -0.8°C | 134 mm | 52% | 2.7 m/s | 3.1 |
| 2009 | 19.4°C | 12.2°C | 5.0°C | 26.5°C | -1.0°C | 22 mm | 50% | 2.4 m/s | 3.6 |
| 2008 | 15.6°C | 9.3°C | 3.1°C | 20.9°C | -3.0°C | 69 mm | 56% | 2.5 m/s | 3.3 |
| 2007 | 15.5°C | 8.7°C | 1.9°C | 22.9°C | -6.6°C | 26 mm | 50% | 2.5 m/s | 3.2 |
| 2006 | 20.0°C | 12.4°C | 4.8°C | 24.9°C | -1.5°C | 1 mm | 26% | 2.4 m/s | 3.8 |
| 2005 | 18.3°C | 12.0°C | 5.7°C | 25.0°C | -0.4°C | 75 mm | 61% | 2.2 m/s | 3 |
| 2004 | 18.2°C | 11.7°C | 5.2°C | 24.4°C | -0.8°C | 29 mm | 50% | 2.2 m/s | 3.1 |
| 2003 🔥 | 23.0°C | 15.1°C | 7.1°C | 28.6°C | 1.1°C | 6 mm | 43% | 2.4 m/s | 3.7 |
| 2002 | 18.0°C | 10.7°C | 3.4°C | 26.2°C | -4.7°C | 4 mm | 40% | 2.1 m/s | 3.3 |
| 2001 | 15.6°C | 9.4°C | 3.1°C | 24.4°C | -2.9°C | 50 mm | 57% | 2.2 m/s | 3.2 |
| 2000 | 20.7°C | 13.1°C | 5.5°C | 28.4°C | -2.8°C | 6 mm | 32% | 2.1 m/s | 3.5 |
| 1999 | 20.3°C | 12.5°C | 4.7°C | 26.6°C | -0.9°C | 2 mm | 34% | 2.2 m/s | 3.6 |
| 1998 | 18.2°C | 11.2°C | 4.2°C | 23.5°C | -1.4°C | 12 mm | 54% | 1.7 m/s | 3.4 |
| 1997 | 16.9°C | 10.6°C | 4.4°C | 24.3°C | -3.1°C | 45 mm | 58% | 2.3 m/s | 3.1 |
| 1996 | 19.6°C | 12.0°C | 4.4°C | 26.1°C | -1.4°C | 10 mm | 32% | 2.4 m/s | 3.4 |
| 1995 | 15.2°C | 9.3°C | 3.4°C | 21.7°C | -2.4°C | 78 mm | 68% | 2.4 m/s | 3 |
| 1994 | 19.1°C | 11.4°C | 3.7°C | 25.2°C | -1.1°C | 4 mm | 41% | 2.3 m/s | 3.6 |
| 1993 🌧️ | 15.8°C | 10.6°C | 5.5°C | 21.9°C | -1.3°C | 198 mm | 76% | 2.6 m/s | 2.8 |
| 1992 | 15.2°C | 8.6°C | 2.0°C | 21.8°C | -3.4°C | 92 mm | 64% | 3.4 m/s | 3.5 |
| 1991 | 16.3°C | 9.8°C | 3.2°C | 20.7°C | -4.1°C | 37 mm | 59% | 2 m/s | 3.4 |
| 1990 | 17.3°C | 10.0°C | 2.7°C | 26.1°C | -2.3°C | 32 mm | 47% | 2.5 m/s | 3.6 |
| 1989 | 16.9°C | 9.9°C | 2.9°C | 22.6°C | -3.5°C | 45 mm | 50% | 2.6 m/s | 3.3 |
| 1988 | 16.7°C | 9.7°C | 2.7°C | 23.4°C | -4.5°C | 38 mm | 52% | 2.7 m/s | 3.2 |
| 1987 | 16.6°C | 9.4°C | 2.3°C | 26.0°C | -4.6°C | 37 mm | 52% | 2.5 m/s | 3.4 |
| 1986 | 21.6°C | 14.0°C | 6.3°C | 26.6°C | 0.1°C | 11 mm | 47% | 2.8 m/s | 3.5 |
| 1985 ❄️ | 14.8°C | 8.5°C | 2.3°C | 20.0°C | -5.1°C | 54 mm | 67% | 2.6 m/s | 3.2 |
| 1984 | 17.5°C | 10.6°C | 3.8°C | 24.2°C | -2.9°C | 19 mm | 59% | 2.9 m/s | 3.5 |
| 1983 | 18.3°C | 11.1°C | 3.9°C | 23.9°C | -1.6°C | 50 mm | 55% | 2.8 m/s | — |
| 1982 | 16.7°C | 10.1°C | 3.4°C | 27.6°C | -2.5°C | 64 mm | 57% | 2.3 m/s | — |
| 1981 | 19.3°C | 12.6°C | 6.0°C | 25.7°C | -1.1°C | 34 mm | 46% | 2.8 m/s | — |
Actual recorded January data for each year, 1981–2025 — sourced from NASA POWER.
The average high in January is around 18.1°C with lows near 4.2°C (mean 11.2°C), based on 45 years of NASA POWER data.
January averages 36 mm of rainfall in San Tan Valley, about average for rainfall. The wettest on record was 198 mm in 1993.
The hottest January reached 28.6°C in 2003. The coldest dipped to -6.6°C in 2007.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average January temperatures have risen by about 0.4°C. Daytime highs moved from 17.3°C to 17.9°C and overnight lows from 3.9°C to 4.1°C over the same span.
January is one of the cooler months of the year in San Tan Valley and about average for rainfall, so plan for around 18.1°C daytime highs and 4.2°C at night.
Yes — January is the coldest month of the year in San Tan Valley, averaging 11.2°C.
For January in San Tan Valley, pack warm layers and a jacket for chilly mornings, with typical highs of 18.1°C and lows of 4.2°C.
Relative humidity in January averages 49% — relatively dry.
Average wind speed in January is 2.4 m/s. The windiest January on record averaged 3.4 m/s (1992).
The wettest January on record was 1993 with 198 mm. On average, January sees 36 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 San Tan 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.
