Upper Alton weather in December

In December, Upper Alton sees average daytime highs of 42°F and overnight lows near 28°F, with 2.4 in of precipitation across 8.1 wet days and about 9.3 hours of daylight. It is the 11th-warmest and 11th-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 29% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 30 min at the start of December to 9 h 18 min by month's end. Set against the rest of the year, December is Upper Alton's 11th-clearest and 6th-windiest month. For the whole year in context, see Upper Alton's year-round climate.

Daytime high
42°
11th warmest
Overnight low
28°
3rd coldest
Precipitation
2.4 in
8.1 wet days
Daylight
9 h 18 min
7:18 AM – 4:35 PM
Cloud cover
65%
11th clearest
Wind
8 mph
6th windiest
Solar energy
1.88 kWh/m²
Travel score
0.4
out of 10

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 Upper Alton reaches about 42°F in the afternoon and slips back to 28°F overnight — a 14°F spread between the day's warmth and the night's chill. On most days the high lands between 28°F and 57°F. Set against its neighbours, December runs about 11°F cooler than November and about 4°F warmer than January.

20°40°60°151015202531
Avg high (°F)Avg low (°F)
14732
24731
34631
44631
54530
64530
74430
84429
94429
104329
114329
124329
134228
144228
154228
164228
174228
184128
194127
204127
214127
224127
234127
244026
254026
264026
274026
284026
294026
304025
313925

How December really feels in Upper Alton

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.

Upper Alton weather by month

How December compares with the rest of the year at a glance. December is the 11th-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan38° / 24°2.68.23.29.60.0
Feb43° / 27°2.47.6310.50.6
Mar54° / 36°3.610.41.511.73.3
Apr66° / 47°4.611.60.2135.7
May75° / 58°5.013.5014.16.2
Jun83° / 67°4.010.9014.75.6
Jul87° / 70°3.29.5014.45.0
Aug85° / 67°2.98.9013.55.5
Sep79° / 59°3.37.5012.37.2
Oct67° / 48°3.38.40.1116.5
Nov53° / 37°3.68.60.79.93.2
Dec42° / 28°2.48.12.39.30.4

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 29% 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 60%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14357
24357
34258
44159
54159
64159
74159
84060
93961
103961
113961
123961
133961
143862
153961
163961
173961
183862
193961
203961
213961
223862
233862
243763
253862
263862
273862
283763
293862
303862
313862

Chance of precipitation in December

Any precipitationSnow

Upper Alton gets around 2.4 in of rain and snow over 8.1 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 27% and peaks near 28% on the wettest days, and about 2 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
1286
2287
3287
4287
5277
6277
7278
8278
9288
10288
11288
12288
13287
14287
15287
16287
17287
18287
19277
20277
21267
22267
23267
24257
25257
26257
27257
28257
29257
30258
31258

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
7982
8982
9982
10982
11991
12991
13991
14991
15991
16991
171000
181000
191000
201000
211000
221000
231000
241000
251000
261000
27991
28991
29991
30991
31991

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 30 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 12 minutes over December. Sunrise moves from 7:06 AM to 7:25 AM, and sunset from 4:35 PM to 4:43 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.57:064:35
29.57:074:34
39.47:084:34
49.47:094:34
59.47:104:34
69.47:114:34
79.47:124:34
89.47:124:34
99.37:134:34
109.37:144:34
119.37:154:34
129.37:154:34
139.37:164:35
149.37:174:35
159.37:184:35
169.37:184:35
179.37:194:36
189.37:194:36
199.37:204:36
209.37:214:37
219.37:214:37
229.37:224:38
239.37:224:38
249.37:224:39
259.37:234:39
269.37:234:40
279.37:244:40
289.37:244:41
299.37:244:42
309.37:244:42
319.37:254:43

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.88 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.88 kWh/m² to a high of 6.44 kWh/m² in June across the year — December's 1.88 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
12.0Dim
22.0Dim
32.0Dim
41.9Dim
51.9Dim
61.9Dim
71.9Dim
81.9Dim
91.9Dim
101.9Dim
111.9Dim
121.9Dim
131.9Dim
141.9Dim
151.9Dim
161.9Dim
171.9Dim
181.9Dim
191.9Dim
201.9Dim
211.9Dim
221.9Dim
231.9Dim
241.9Dim
251.9Dim
261.9Dim
271.9Dim
281.9Dim
291.9Dim
301.9Dim
311.9Dim
Planning a trip in December

Is December a good time to visit Upper Alton?

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

0.4
Sightseeing
11th-best month of the year
0.0
Beach & pool
10th-best month of the year

December is a weaker month for outdoor sightseeing in Upper Alton.

What to pack for Upper Alton in December

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

In December, Upper Alton sees daytime highs around 42°F and nights near 28°F. Pack a warm layer and a heavy coat. Worth having: rain gear. About 8 days see rain.

a warm layera heavy coatrain gear

UV index in Upper Alton 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 Upper Alton peaks around June 21 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 23 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateJun 21UV 9Dec 23UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr7High
May8Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep7High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in Upper Alton 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 Upper Alton is worst in August — around 18 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (October, 8 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodModerateGoodAug 1018 µg/m³Oct 228 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb13Moderate
Mar13Moderate
Apr11Good
May14Moderate
Jun16Moderate
Jul18Moderate
Aug18Moderate
Sep13Moderate
Oct8Good
Nov9Good
Dec10Good
Location & terrain

Where is Upper Alton?

Upper Alton sits at 38.9°N, 90.2°W, 545 ft above sea level, in United States. The nearest listed city is Alton, 2.5 mi away.

Topography around Upper Alton

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

Within 2 miles, the terrain around Upper Alton has only modest variations in elevation — a maximum elevation change of 249 ft around an average of 518 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 620 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 751 ft.

The land around Upper Alton is covered by trees (55%) and artificial surfaces (22%) within 2 miles, trees (41%) and cropland (32%) within 10 miles, and cropland (49%) and trees (37%) within 50 miles.

2 miles
249 ft
10 miles
620 ft
50 miles
751 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Alton 2.5 mi · Godfrey 3.7 mi · Old Jamestown 8.7 mi · Spanish Lake 9.3 mi · Florissant 12 mi · Edwardsville 12 mi · Ferguson 14 mi · Granite City 14 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 Upper Alton (38.9114°, -90.1507°, elevation 545 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).