Climate averages 1991–2020
San Tan Valley weather
in December.
A mild, fairly dry month: the coolest and the 10th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
December is a mild month in San Tan Valley: daytime highs average 17.6°C and nights cool to about 4.8°C. By daytime temperature it is the coolest month of the year.
Expect about 34 mm of rain on roughly 4 days, which makes December a fairly dry month (the 10th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 10 h 00 min on an average December day.
The nearest other city in this atlas is Chandler (32 km away). In December its highs average 18.1°C, about as warm as San Tan Valley, with 27 mm of rain.
Among the 498 cities listed in the United States, San Tan Valley ranks joint 79th of 498 for the warmest December highs and joint 62nd of 498 for the driest December (rainfall, lowest first). The mean December high of those 498 cities is 10.5°C; San Tan Valley is 7.1°C warmer than that mean.
From December to January, average highs rise by 0.6°C to 18.2°C, and monthly rainfall rises from 34 mm to 38 mm.
The annual picture
December in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
San Tan Valley climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 18.2°C4.9°C | 4.9°C | 38 | 4.2 | 10.210 h |
| February | 19.8°C6.3°C | 6.3°C | 41 | 4.4 | 11.011 h |
| March | 23.8°C8.9°C | 8.9°C | 27 | 3.0 | 12.012 h |
| April | 28.2°C12.5°C | 12.5°C | 8.4 | 1.4 | 13.013 h |
| May | 33.2°C17.4°C | 17.4°C | 4.1 | 0.7 | 13.914 h |
| June | 38.7°C22.6°C | 22.6°C | 2.0 | 0.6 | 14.314 h |
| July | 39.3°C26.5°C | 26.5°C | 21 | 3.7 | 14.114 h |
| August | 38.4°C26.2°C | 26.2°C | 27 | 4.9 | 13.413 h |
| September | 35.9°C22.7°C | 22.7°C | 26 | 3.2 | 12.412 h |
| October | 30.0°C15.9°C | 15.9°C | 18 | 2.4 | 11.411 h |
| November | 23.3°C9.6°C | 9.6°C | 19 | 2.4 | 10.510 h |
| December, selected | 17.6°C4.8°C | 4.8°C | 34 | 4.3 | 10.010 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
December in nearby cities
- Chandler in DecemberUnited States · 32 kmHigh 18.1°C · Low 4.5°C · 27 mm rain
- Mesa in DecemberUnited States · 38 kmHigh 17.8°C · Low 4.2°C · 33 mm rain
- Tempe in DecemberUnited States · 43 kmHigh 17.8°C · Low 4.3°C · 28 mm rain
- Scottsdale in DecemberUnited States · 49 kmHigh 17.7°C · Low 4.6°C · 28 mm rain
- Phoenix in DecemberUnited States · 58 kmHigh 17.8°C · Low 4.5°C · 28 mm rain
- Glendale (Arizona), United States in DecemberUnited States · 72 kmHigh 17.7°C · Low 4.8°C · 25 mm rain
- Peoria (Arizona), United States in DecemberUnited States · 79 kmHigh 17.7°C · Low 5.0°C · 25 mm rain
- Avondale in DecemberUnited States · 81 kmHigh 18.2°C · Low 4.9°C · 25 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for San Tan Valley) is explained once on the San Tan Valley year overview and on the Sources, method and limits page.