O'Fallon Weather in December
Average highs run from 48°F on December 1 to 40°F on December 31, and lows from 30°F to 23°F. Normal precipitation for the month is 2.56 in over about 9 wet days.
December day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
December at a glance
- Average high
- 44°F
- Average low
- 27°F
- Precipitation
- 2.56 in
- Snowfall
- 2.7 in
- Record high
- 77°FDec 28, 2025
- Record low
- -22°FDec 23, 1989
- Chance of a freeze
- 100%
- Daylight
- 9 h 39 min to 9 h 30 min
- Cloud cover
- 66%
- Humidity
- 83%
- Dew point
- 28°F
- Wind
- 9.2 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.
| Date | Normal high | Normal low | Record high | Record low | Chance wet | Chance of snow |
|---|---|---|---|---|---|---|
| Dec 1 | 48°F | 30°F | 71°F 2012 | 14°F 2002 | 29% | 5% |
| Dec 2 | 48°F | 30°F | 75°F 2012 | 13°F 2025 | 29% | 5% |
| Dec 3 | 48°F | 30°F | 76°F 2021 | 12°F 2025 | 29% | 5% |
| Dec 4 | 47°F | 30°F | 74°F 2001 | 10°F 1991 | 29% | 6% |
| Dec 5 | 47°F | 29°F | 75°F 1998 | 9°F 2025 | 29% | 6% |
| Dec 6 | 46°F | 29°F | 73°F 1998 | 11°F 2002 | 29% | 6% |
| Dec 7 | 46°F | 29°F | 68°F 1991 | 11°F 2005 | 29% | 6% |
| Dec 8 | 46°F | 29°F | 75°F 1991 | 8°F 2005 | 29% | 6% |
| Dec 9 | 45°F | 28°F | 68°F 2021 | -2°F 2005 | 29% | 7% |
| Dec 10 | 45°F | 28°F | 69°F 2015 | 10°F 2009 | 29% | 7% |
| Dec 11 | 45°F | 28°F | 68°F 1990 | 9°F 2013 | 29% | 7% |
| Dec 12 | 45°F | 27°F | 72°F 2015 | 4°F 1989 | 29% | 7% |
| Dec 13 | 44°F | 27°F | 68°F 2015 | 3°F 2010 | 29% | 7% |
| Dec 14 | 44°F | 27°F | 68°F 2021 | -1°F 2010 | 29% | 7% |
| Dec 15 | 44°F | 27°F | 72°F 2021 | -6°F 1989 | 29% | 7% |
| Dec 16 | 43°F | 26°F | 71°F 2021 | -11°F 1989 | 29% | 7% |
| Dec 17 | 43°F | 26°F | 64°F 2002 | -10°F 1989 | 29% | 8% |
| Dec 18 | 43°F | 26°F | 63°F 2002 | -4°F 1989 | 29% | 8% |
| Dec 19 | 43°F | 26°F | 63°F 1988 | -4°F 1989 | 29% | 8% |
| Dec 20 | 42°F | 25°F | 70°F 2013 | -8°F 1989 | 29% | 8% |
| Dec 21 | 42°F | 25°F | 65°F 2015 | -13°F 1989 | 29% | 8% |
| Dec 22 | 42°F | 25°F | 62°F 2007 | -18°F 1989 | 29% | 8% |
| Dec 23 | 42°F | 25°F | 68°F 2025 | -22°F 1989 | 29% | 8% |
| Dec 24 | 41°F | 25°F | 74°F 2021 | -5°F 1989 | 28% | 8% |
| Dec 25 | 41°F | 24°F | 72°F 2019 | 1°F 1990 | 28% | 8% |
| Dec 26 | 41°F | 24°F | 70°F 2019 | 2°F 2002 | 28% | 8% |
| Dec 27 | 41°F | 24°F | 70°F 2008 | 1°F 2017 | 28% | 8% |
| Dec 28 | 41°F | 24°F | 77°F 2025 | -1°F 2000 | 28% | 8% |
| Dec 29 | 40°F | 23°F | 67°F 2022 | 6°F 1988 | 28% | 8% |
| Dec 30 | 40°F | 23°F | 69°F 2002 | 5°F 1990 | 28% | 8% |
| Dec 31 | 40°F | 23°F | 70°F 2004 | 2°F 2017 | 28% | 8% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (CST).
- December 1
- sunrise 7:02 AM, sunset 4:41 PM
- December 31
- sunrise 7:21 AM, sunset 4:51 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00237475 (St Peters 2 Se), public domain. Records: NOAA GHCN-Daily, station USW00003966, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.