Oconomowoc weather in December

In December, Oconomowoc sees average daytime highs of 33°F and overnight lows near 20°F, with 2.0 in of precipitation across 7.7 wet days and about 8.9 hours of daylight. It is the 10th-warmest and 10th-wettest month of the year here.

Highs ease over the month, from about 37°F in the first days to 30°F by the end. The sky is clear or mostly clear about 22% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 hours at the start of December to 8 h 54 min by month's end. Set against the rest of the year, December is Oconomowoc's 11th-clearest and 7th-windiest month. For the whole year in context, see Oconomowoc's year-round climate.

Daytime high
33°
10th warmest
Overnight low
20°
3rd coldest
Precipitation
2.0 in
7.7 wet days
Daylight
8 h 48 min
7:25 AM – 4:15 PM
Cloud cover
70%
11th clearest
Wind
8 mph
7th windiest
Solar energy
1.55 kWh/m²
Travel score
0.0
out of 10

Oconomowoc is city in Waukesha County, Wisconsin, United States.

Founded
1837

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 37°F in the first days to 30°F by the end.

A typical December day in Oconomowoc reaches about 33°F in the afternoon and slips back to 20°F overnight — a 13°F spread between the day's warmth and the night's chill. On most days the high lands between 19°F and 46°F. Set against its neighbours, December runs about 12°F cooler than November and about 5°F warmer than January.

20°40°60°151015202531
Avg high (°F)Avg low (°F)
13825
23724
33724
43624
53623
63523
73522
83522
93422
103421
113421
123321
133320
143320
153320
163220
173220
183219
193219
203219
213119
223119
233119
243118
253118
263118
273118
283017
293017
303017
313017

How December really feels in Oconomowoc

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
27 feel bitter (≤ 14°F)

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

Oconomowoc weather by month

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

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan28° / 14°1.78.26.89.20.0
Feb32° / 17°1.775.710.20.0
Mar44° / 27°2.39.44.111.60.9
Apr56° / 38°3.911.91.613.13.7
May68° / 49°3.811.9014.45.9
Jun78° / 59°3.811.4015.16.5
Jul81° / 64°3.49.7014.96.5
Aug79° / 62°3.510.3013.86.7
Sep72° / 54°2.98.5012.36.9
Oct59° / 42°2.890.310.84.7
Nov45° / 31°2.18.229.51.0
Dec33° / 20°2.07.75.18.90.0

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 22% 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 67%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13466
23466
33367
43466
53466
63466
73466
83466
93466
103466
113466
123466
133268
143268
153268
163268
173268
183169
193268
203268
213268
223169
233169
243169
253169
263169
273169
283169
293268
303268
313268

Chance of precipitation in December

Any precipitationSnow

Oconomowoc gets around 2.0 in of rain and snow over 7.7 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 25% and peaks near 29% on the wettest days, and about 5 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
12914
22915
32815
42816
52816
62716
72717
82717
92616
102616
112516
122516
132516
142516
152516
162415
172415
182415
192415
202415
212315
222315
232315
242316
252316
262316
272416
282417
292417
302417
312417

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 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)
1100
2100
3100
4100
5100
6100
7100
8100
9100
10100
11100
12100
13100
14100
15100
16100
17100
18100
19100
20100
21100
22100
23100
24100
25100
26100
27100
28100
29100
30100
31100

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.

051015151015202531
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 hours at the start of December to 8 h 54 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 7:12 AM to 7:32 AM, and sunset from 4:15 PM to 4:23 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.07:124:15
29.07:134:15
39.07:144:15
49.07:154:14
59.07:164:14
68.97:174:14
78.97:184:14
88.97:194:14
98.97:204:14
108.97:214:14
118.97:224:14
128.97:224:14
138.97:234:14
148.87:244:15
158.87:254:15
168.87:254:15
178.87:264:15
188.87:274:16
198.87:274:16
208.87:284:16
218.87:284:17
228.87:294:17
238.87:294:18
248.87:304:18
258.87:304:19
268.87:304:19
278.87:314:20
288.87:314:21
298.87:314:21
308.87:314:22
318.97:324:23

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.55 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.55 kWh/m² to a high of 6.29 kWh/m² in June across the year — December's 1.55 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.6Dim
21.6Dim
31.6Dim
41.6Dim
51.6Dim
61.6Dim
71.6Dim
81.6Dim
91.6Dim
101.6Dim
111.6Dim
121.6Dim
131.6Dim
141.6Dim
151.5Dim
161.5Dim
171.5Dim
181.5Dim
191.5Dim
201.5Dim
211.5Dim
221.5Dim
231.5Dim
241.5Dim
251.5Dim
261.6Dim
271.6Dim
281.6Dim
291.6Dim
301.6Dim
311.6Dim
Planning a trip in December

Is December a good time to visit Oconomowoc?

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

0.0
Sightseeing
10th-best month of the year
0.0
Beach & pool
8th-best month of the year

December is a weaker month for outdoor sightseeing in Oconomowoc.

What to pack for Oconomowoc in December

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

In December, Oconomowoc sees daytime highs around 33°F and nights near 20°F. Pack a warm layer and a heavy coat. About 8 days see rain.

a warm layera heavy coat

Sea temperature near Oconomowoc in December

The nearest coast averages about 41°F in December — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 32 mi away) is warmest in August at about 70°F and coldest in March near 36°F.

It's comfortable for a long swim from Jul 29 to Aug 30 — about 1.1 months when the water holds above 68°F.

30°40°50°60°70°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarm
Sea temperature (°F)Comfort
Jan38Bracing
Feb36Bracing
Mar36Bracing
Apr38Bracing
May42Bracing
Jun54Bracing
Jul67Cool
Aug70Refreshing
Sep66Cool
Oct56Bracing
Nov46Bracing
Dec41Bracing

UV index in Oconomowoc in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 1. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Oconomowoc peaks around June 20 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 1 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 20UV 9Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar4Moderate
Apr6High
May8Very high
Jun9Very high
Jul8Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov2Low
Dec1Low

Air quality in Oconomowoc 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 Oconomowoc is worst in July — around 17 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (October, 9 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodJul 1616 µg/m³Oct 239 µg/m³
PM2.5 (µg/m³)Level
Jan12Good
Feb14Moderate
Mar15Moderate
Apr13Moderate
May15Moderate
Jun16Moderate
Jul17Moderate
Aug15Moderate
Sep12Moderate
Oct9Good
Nov9Good
Dec10Good
Location & terrain

Where is Oconomowoc?

Oconomowoc sits at 43.1°N, 88.5°W, 863 ft above sea level, in United States. The nearest listed city is Watertown, 13 mi away.

Topography around Oconomowoc

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

Within 2 miles, the terrain around Oconomowoc has only modest variations in elevation — a maximum elevation change of 148 ft around an average of 879 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 440 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 846 ft.

The land around Oconomowoc is covered by trees (35%), grassland (23%) and artificial surfaces (20%) within 2 miles, trees (36%), cropland (31%) and grassland (24%) within 10 miles, and cropland (44%) and trees (23%) within 50 miles.

2 miles
148 ft
10 miles
440 ft
50 miles
846 ft
treesgrasslandcroplandartificial surfaceswaterwetland
December weather nearby: Watertown 13 mi · Waukesha 15 mi · Menomonee Falls 20 mi · Brookfield 20 mi · Germantown 21 mi · New Berlin 22 mi · Muskego 23 mi · Mequon 25 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 Oconomowoc (43.1117°, -88.4993°, elevation 863 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. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. 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).