Round Lake weather in December

In December, Round Lake sees average daytime highs of 35°F and overnight lows near 25°F, with 2.4 in of precipitation across 8.8 wet days and about 9 hours of daylight. It is the 10th-warmest and 10th-wettest month of the year here.

Highs ease over the month, from about 39°F in the first days to 33°F by the end. The sky is clear or mostly clear about 21% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 06 min at the start of December to 8 h 54 min by month's end. Set against the rest of the year, December is Round Lake's 11th-clearest and 3rd-windiest month. For the whole year in context, see Round Lake's year-round climate.

Daytime high
35°
10th warmest
Overnight low
25°
3rd coldest
Precipitation
2.4 in
8.8 wet days
Daylight
8 h 54 min
7:21 AM – 4:16 PM
Cloud cover
70%
11th clearest
Wind
10 mph
3rd windiest
Solar energy
1.56 kWh/m²
Travel score
0.0
out of 10

Round Lake is village in Lake County, Illinois, United States of America.

Founded
1908

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 39°F in the first days to 33°F by the end.

A typical December day in Round Lake reaches about 35°F in the afternoon and slips back to 25°F overnight — a 10°F spread between the day's warmth and the night's chill. On most days the high lands between 22°F and 47°F. Set against its neighbours, December runs about 11°F cooler than November and about 5°F warmer than January.

20°40°60°151015202531
Avg high (°F)Avg low (°F)
14029
23929
33929
43828
53828
63827
73727
83727
93726
103626
113626
123626
133525
143525
153525
163525
173524
183524
193424
203424
213424
223424
233423
243323
253323
263323
273322
283322
293322
303322
313222

How December really feels in Round Lake

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
15 feel bitter (≤ 14°F)

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

Round Lake 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
Jan30° / 19°2.39.16.49.30.0
Feb33° / 20°2.07.25.310.30.0
Mar42° / 29°2.69.73.211.60.6
Apr53° / 40°4.412.21.213.12.9
May64° / 51°4.112.3014.45.3
Jun76° / 62°3.611.40156.5
Jul80° / 67°3.310.8014.86.4
Aug79° / 66°3.610.7013.76.7
Sep72° / 58°2.99012.36.9
Oct60° / 46°3.39.50.110.84.8
Nov46° / 35°2.68.51.49.61.4
Dec35° / 25°2.48.84.590.0

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 21% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 12% of December, with mostly cloudy or overcast conditions the remaining 68%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13268
23367
33367
43268
53367
63367
73367
83367
93466
103367
113367
123367
133466
143367
153367
163367
173367
183268
193268
203268
213268
223367
233367
243268
253268
263268
273169
283169
293070
303070
313070

Chance of precipitation in December

Any precipitationSnow

Round Lake gets around 2.4 in of rain and snow over 8.8 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 29% and peaks near 31% on the wettest days, and about 5 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
13112
23113
33113
43113
53114
63014
73014
83014
93014
102914
112914
122914
132914
142814
152814
162814
172814
182813
192813
202813
212813
222814
232814
242814
252814
262815
272815
282916
292916
302916
312917

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 10 mph in December.

Across December, daily wind ranges from about 10 mph on the calmest days to 11 mph at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (mph)Feels
111light breeze
211light breeze
311light breeze
410light breeze
510light breeze
610light breeze
710light breeze
810light breeze
910light breeze
1010light breeze
1110light breeze
1210light breeze
1310light breeze
1410light breeze
1510light breeze
1610light breeze
1710light breeze
1810light breeze
1910light breeze
2010light breeze
2110light breeze
2210light breeze
2311light breeze
2411light breeze
2511light breeze
2611light breeze
2711light breeze
2811light breeze
2911light breeze
3011light breeze
3111light breeze

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 06 min 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 12 minutes over December. Sunrise moves from 7:08 AM to 7:27 AM, and sunset from 4:16 PM to 4:24 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.17:084:16
29.17:094:16
39.17:104:16
49.17:114:15
59.17:124:15
69.07:134:15
79.07:144:15
89.07:154:15
99.07:164:15
109.07:174:15
119.07:174:15
128.97:184:15
138.97:194:15
148.97:204:16
158.97:204:16
168.97:214:16
178.97:224:16
188.97:224:17
198.97:234:17
208.97:234:17
218.97:244:18
228.97:244:18
238.97:254:19
248.97:254:19
258.97:264:20
268.97:264:20
278.97:264:21
288.97:274:22
298.97:274:22
308.97:274:23
318.97:274:24

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.56 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.56 kWh/m² to a high of 6.4 kWh/m² in June across the year — December's 1.56 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.7Dim
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
261.5Dim
271.5Dim
281.6Dim
291.6Dim
301.6Dim
311.6Dim
Planning a trip in December

Is December a good time to visit Round Lake?

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
9th-best month of the year

December is a weaker month for outdoor sightseeing in Round Lake.

What to pack for Round Lake in December

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

In December, Round Lake sees daytime highs around 35°F and nights near 25°F. Pack a warm layer and a heavy coat. Worth having: rain gear. About 9 days see rain.

a warm layera heavy coatrain gear

Sea temperature near Round Lake in December

The nearest coast averages about 42°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 11 mi away) is warmest in August at about 71°F and coldest in March near 36°F.

It's comfortable for a long swim from Jul 18 to Sep 8 — about 1.7 months when the water holds above 68°F.

30°40°50°60°70°80°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°F)Comfort
Jan38Bracing
Feb36Bracing
Mar36Bracing
Apr38Bracing
May43Bracing
Jun55Bracing
Jul68Refreshing
Aug71Refreshing
Sep67Cool
Oct57Bracing
Nov47Bracing
Dec42Bracing

UV index in Round Lake 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 Round Lake peaks around June 22 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 22UV 9Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar4Moderate
Apr6High
May7Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Round Lake 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 Round Lake is worst in July — around 21 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (October, 10 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodJul 921 µg/m³Oct 2410 µg/m³
PM2.5 (µg/m³)Level
Jan12Moderate
Feb15Moderate
Mar18Moderate
Apr19Moderate
May20Moderate
Jun21Moderate
Jul21Moderate
Aug18Moderate
Sep15Moderate
Oct10Good
Nov10Good
Dec11Good
Location & terrain

Where is Round Lake?

Round Lake sits at 42.4°N, 88.1°W, 797 ft above sea level, in United States. The nearest listed city is Round Lake Beach, 1.2 mi away.

Topography around Round Lake

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

Within 2 miles, the terrain around Round Lake has only modest variations in elevation — a maximum elevation change of 125 ft around an average of 784 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 302 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 827 ft.

The land around Round Lake is covered by trees (31%), grassland (29%) and artificial surfaces (28%) within 2 miles, trees (37%) and grassland (29%) within 10 miles, and water (30%), cropland (26%) and trees (20%) within 50 miles.

2 miles
125 ft
10 miles
302 ft
50 miles
827 ft
treesgrasslandcroplandartificial surfaceswater
December weather nearby: Round Lake Beach 1.2 mi · Grayslake 2.5 mi · Mundelein 7.5 mi · Libertyville 8.7 mi · McHenry 8.7 mi · Gurnee 9.9 mi · Lake Zurich 11 mi · Vernon Hills 11 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 Round Lake (42.3534°, -88.0934°, elevation 797 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).