Mason City Weather in December
Average highs run from 43°F on December 1 to 34°F on December 31, and lows from 25°F to 19°F. Normal precipitation for the month is 1.70 in over about 6 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
- 38°F
- Average low
- 22°F
- Precipitation
- 1.70 in
- Snowfall
- 2.6 in
- Record high
- 72°FDec 3, 1970
- Record low
- -29°FDec 26, 1914
- Chance of a freeze
- 100%
- Daylight
- 9 h 31 min to 9 h 22 min
- Cloud cover
- 67%
- Humidity
- 84%
- Dew point
- 26°F
- Wind
- 11.2 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 | 43°F | 25°F | 64°F 1941 | 8°F 1964 | 23% | 6% |
| Dec 2 | 43°F | 25°F | 68°F 1950 | 0°F 1942 | 23% | 6% |
| Dec 3 | 43°F | 25°F | 72°F 1970 | -8°F 1929 | 23% | 6% |
| Dec 4 | 42°F | 24°F | 69°F 1916 | -7°F 2025 | 23% | 6% |
| Dec 5 | 42°F | 24°F | 72°F 1998 | -7°F 2025 | 23% | 7% |
| Dec 6 | 41°F | 24°F | 70°F 1980 | -2°F 1977 | 23% | 7% |
| Dec 7 | 41°F | 24°F | 68°F 1916 | -3°F 2005 | 23% | 7% |
| Dec 8 | 40°F | 23°F | 65°F 1946 | -3°F 1909 | 23% | 7% |
| Dec 9 | 40°F | 23°F | 69°F 1918 | -10°F 1958 | 22% | 8% |
| Dec 10 | 40°F | 23°F | 65°F 1918 | -11°F 1917 | 22% | 8% |
| Dec 11 | 39°F | 23°F | 66°F 1949 | -18°F 1917 | 22% | 8% |
| Dec 12 | 39°F | 23°F | 67°F 2015 | -12°F 1962 | 22% | 8% |
| Dec 13 | 38°F | 22°F | 64°F 1948 | -6°F 1958 | 22% | 8% |
| Dec 14 | 38°F | 22°F | 67°F 1975 | -13°F 2025 | 22% | 8% |
| Dec 15 | 38°F | 22°F | 70°F 1948 | -16°F 1917 | 22% | 9% |
| Dec 16 | 37°F | 22°F | 64°F 2021 | -17°F 1932 | 22% | 9% |
| Dec 17 | 37°F | 22°F | 64°F 1984 | -10°F 1914 | 22% | 9% |
| Dec 18 | 37°F | 21°F | 63°F 1939 | -8°F 1922 | 22% | 9% |
| Dec 19 | 36°F | 21°F | 60°F 1957 | -15°F 1983 | 22% | 9% |
| Dec 20 | 36°F | 21°F | 63°F 1949 | -13°F 1914 | 22% | 10% |
| Dec 21 | 36°F | 21°F | 62°F 1941 | -12°F 1963 | 21% | 10% |
| Dec 22 | 36°F | 20°F | 61°F 1933 | -12°F 1963 | 21% | 10% |
| Dec 23 | 35°F | 20°F | 65°F 1933 | -12°F 1983 | 21% | 10% |
| Dec 24 | 35°F | 20°F | 65°F 1955 | -19°F 1983 | 21% | 10% |
| Dec 25 | 35°F | 20°F | 64°F 2019 | -18°F 1983 | 21% | 10% |
| Dec 26 | 35°F | 20°F | 65°F 2019 | -29°F 1914 | 21% | 10% |
| Dec 27 | 34°F | 19°F | 69°F 2008 | -8°F 1935 | 21% | 10% |
| Dec 28 | 34°F | 19°F | 70°F 2025 | -24°F 1924 | 21% | 10% |
| Dec 29 | 34°F | 19°F | 72°F 1984 | -12°F 1917 | 21% | 11% |
| Dec 30 | 34°F | 19°F | 61°F 1936 | -15°F 1917 | 21% | 11% |
| Dec 31 | 34°F | 19°F | 62°F 1951 | -9°F 1983 | 21% | 11% |
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 4:33 PM
- December 31
- sunrise 7:21 AM, sunset 4:43 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00115413 (Mason City 4SE), public domain. Records: NOAA GHCN-Daily, station USC00115079, 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.