Mason weather in December

In December, Mason sees average daytime highs of 43°F and overnight lows near 30°F, with 3.8 in of precipitation across 10.4 wet days and about 9.3 hours of daylight. It is the 10th-warmest and 5th-wettest month of the year here.

Highs ease over the month, from about 46°F in the first days to 40°F by the end. The sky is clear or mostly clear about 19% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 24 min at the start of December to 9 h 18 min by month's end. Set against the rest of the year, December is Mason's 11th-clearest and 5th-windiest month. For the whole year in context, see Mason's year-round climate.

Daytime high
43°
10th warmest
Overnight low
30°
3rd coldest
Precipitation
3.8 in
10.4 wet days
Daylight
9 h 12 min
7:56 AM – 5:11 PM
Cloud cover
72%
11th clearest
Wind
8 mph
5th windiest
Solar energy
1.68 kWh/m²
Travel score
0.4
out of 10

Mason is city in Warren County, Ohio, United States.

Density
676/km²
people per km²
Founded
1815

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 46°F in the first days to 40°F by the end.

A typical December day in Mason reaches about 43°F in the afternoon and slips back to 30°F overnight — a 13°F spread between the day's warmth and the night's chill. On most days the high lands between 29°F and 57°F. Set against its neighbours, December runs about 10°F cooler than November and about 4°F warmer than January.

20°40°60°151015202531
Avg high (°F)Avg low (°F)
14733
24633
34633
44632
54532
64532
74431
84431
94431
104331
114330
124330
134330
144230
154229
164229
174229
184229
194229
204229
214129
224128
234128
244128
254128
264128
274128
284128
294028
304027
314027

How December really feels in Mason

Once humidity and wind are folded in, December averages 0 days that feel above 90°F and 31 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
31
wind chill below the day's low

The story in December is cold — wind chill drags the overnight "feels like" below the raw low.

Mason weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan39° / 25°3.410.44.39.50.0
Feb42° / 27°3.09.43.810.50.4
Mar52° / 35°4.211.4211.72.7
Apr65° / 46°4.712.70.5135.3
May73° / 56°4.713.1014.16.2
Jun82° / 65°4.212.2014.75.8
Jul85° / 68°3.511.2014.55.3
Aug83° / 66°2.99.5013.55.9
Sep78° / 59°2.78012.37.2
Oct65° / 47°3.08.50.1116.1
Nov53° / 37°3.49.30.89.83.0
Dec43° / 30°3.810.42.99.30.4

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 19% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 10% of December, with mostly cloudy or overcast conditions the remaining 70%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13367
23367
33268
43070
53070
62971
72971
82872
92872
102872
112773
122773
132773
142872
152872
162773
172872
182872
192872
203070
213070
223070
233070
243070
253070
263070
273070
283070
293070
303169
313169

Chance of precipitation in December

Any precipitationSnow

Mason gets around 3.8 in of rain and snow over 10.4 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 34% and peaks near 35% on the wettest days, and about 3 days bring snow.

0%10%20%30%40%50%151015202531
Rain chance (%)Snow chance (%)
1346
2346
3346
4347
5347
6347
7348
8358
9359
10359
11359
12359
13349
143410
153410
163410
173410
183410
193410
203310
213310
223310
233210
243210
253210
263210
273310
283311
293311
303311
313412

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

Most of December feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, December lands in the dry band about 99% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)
1982
2982
3982
4982
5982
6982
7991
8991
9991
10991
11991
12991
13991
14991
15991
16991
17991
18991
19991
20991
21991
22991
23991
24991
25991
26991
27991
28991
29991
30982
31982

Wind in December

Winds average 8 mph in December.

Across December, daily wind ranges from about 8 mph on the calmest days to 8 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
18light breeze
28light breeze
38light breeze
48light breeze
58light breeze
68light breeze
78light breeze
88light breeze
98light breeze
108light breeze
118light breeze
128light breeze
138light breeze
148light breeze
158light breeze
168light breeze
178light breeze
188light breeze
198light breeze
208light breeze
218light breeze
228light breeze
238light breeze
248light breeze
258light breeze
268light breeze
278light breeze
288light breeze
298light breeze
308light breeze
318light breeze

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 24 min at the start of December to 9 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 6 minutes over December. Sunrise moves from 7:44 AM to 8:03 AM, and sunset from 5:10 PM to 5:18 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.47:445:10
29.47:455:10
39.47:465:10
49.47:475:09
59.47:485:09
69.37:495:09
79.37:505:09
89.37:505:09
99.37:515:09
109.37:525:09
119.37:535:10
129.37:535:10
139.37:545:10
149.37:555:10
159.27:565:10
169.27:565:11
179.27:575:11
189.27:575:11
199.27:585:12
209.27:595:12
219.27:595:12
229.28:005:13
239.28:005:13
249.28:005:14
259.28:015:14
269.28:015:15
279.28:025:16
289.28:025:16
299.28:025:17
309.38:025:18
319.38:035:18

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.68 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.68 kWh/m² to a high of 6.18 kWh/m² in June across the year — December's 1.68 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.8Dim
21.8Dim
31.8Dim
41.8Dim
51.7Dim
61.7Dim
71.7Dim
81.7Dim
91.7Dim
101.7Dim
111.7Dim
121.7Dim
131.7Dim
141.6Dim
151.6Dim
161.6Dim
171.6Dim
181.7Dim
191.7Dim
201.7Dim
211.7Dim
221.7Dim
231.7Dim
241.7Dim
251.7Dim
261.7Dim
271.7Dim
281.7Dim
291.7Dim
301.7Dim
311.7Dim
Planning a trip in December

Is December a good time to visit Mason?

Our two travel scores rate December for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

0.4
Sightseeing
10th-best month of the year
0.0
Beach & pool
10th-best month of the year

December is a weaker month for outdoor sightseeing in Mason.

What to pack for Mason in December

From December's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In December, Mason sees daytime highs around 43°F and nights near 30°F. Pack a warm layer and a heavy coat. Worth having: rain gear. About 10 days see rain.

a warm layera heavy coatrain gear

UV index in Mason in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 2. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Mason peaks around June 21 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateJun 21UV 9Dec 22UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov3Moderate
Dec2Low

Air quality in Mason in December

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where December falls, not just the annual average.

Air quality in Mason is worst in July — around 19 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (October, 8 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1418 µg/m³Oct 248 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb11Good
Mar11Good
Apr12Good
May15Moderate
Jun18Moderate
Jul19Moderate
Aug16Moderate
Sep13Moderate
Oct8Good
Nov9Good
Dec9Good
Location & terrain

Where is Mason?

Mason sits at 39.4°N, 84.3°W, 810 ft above sea level, in United States. The nearest listed city is Lebanon, 7.5 mi away.

Topography around Mason

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Mason.

Within 2 miles, the terrain around Mason has only modest variations in elevation — a maximum elevation change of 240 ft around an average of 817 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 492 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 912 ft.

The land around Mason is covered by grassland (39%), trees (36%) and artificial surfaces (22%) within 2 miles, trees (43%) and grassland (29%) within 10 miles, and trees (42%) and cropland (36%) within 50 miles.

2 miles
240 ft
10 miles
492 ft
50 miles
912 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Lebanon 7.5 mi · Forest Park 11 mi · Middletown 12 mi · Fairfield 14 mi · Hamilton 14 mi · Springboro 14 mi · Norwood 16 mi · White Oak 19 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Mason (39.3601°, -84.3099°, elevation 810 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).