Merrillville weather in December

In December, Merrillville sees average daytime highs of 37°F and overnight lows near 26°F, with 2.4 in of precipitation across 9.1 wet days and about 9.1 hours of daylight. It is the 10th-warmest and 11th-wettest month of the year here.

Highs ease over the month, from about 41°F in the first days to 34°F by the end. The sky is clear or mostly clear about 18% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 12 min at the start of December to 9 hours by month's end. Set against the rest of the year, December is Merrillville's 11th-clearest and 3rd-windiest month. For the whole year in context, see Merrillville's year-round climate.

Daytime high
37°
10th warmest
Overnight low
26°
3rd coldest
Precipitation
2.4 in
9.1 wet days
Daylight
9 hours
7:15 AM – 4:16 PM
Cloud cover
73%
11th clearest
Wind
10 mph
3rd windiest
Solar energy
1.6 kWh/m²
Travel score
0.0
out of 10

Merrillville is town in Ross Township, Lake County, Indiana.

Density
409/km²
people per km²
Founded
1971

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 41°F in the first days to 34°F by the end.

A typical December day in Merrillville reaches about 37°F in the afternoon and slips back to 26°F overnight — a 11°F spread between the day's warmth and the night's chill. On most days the high lands between 23°F and 50°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)
14230
24130
34129
44029
54029
64028
73928
83928
93828
103827
113827
123727
133726
143726
153726
163726
173625
183625
193625
203625
213625
223525
233524
243524
253524
263524
273524
283524
293424
303423
313423

How December really feels in Merrillville

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
8 feel bitter (≤ 14°F)

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

Merrillville weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan32° / 20°2.69.76.79.30.0
Feb35° / 22°2.17.75.210.30.0
Mar45° / 31°3.010.43.211.71.1
Apr57° / 41°4.212.2113.13.8
May68° / 52°4.412.6014.35.9
Jun78° / 62°4.011.8014.96.4
Jul82° / 67°3.912.1014.76.2
Aug80° / 65°3.810.7013.76.6
Sep74° / 57°3.18.9012.37.0
Oct62° / 46°3.39.90.210.95.2
Nov48° / 35°2.99.41.59.71.8
Dec37° / 26°2.49.14.49.10.0

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 18% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 11% of December, with mostly cloudy or overcast conditions the remaining 71%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13070
23070
33070
43070
53070
63070
72971
82971
92971
102971
112971
122971
132872
142971
152971
162971
172971
182872
192872
202872
212872
222872
232872
242971
252971
262872
272872
282872
292773
302773
312773

Chance of precipitation in December

Any precipitationSnow

Merrillville gets around 2.4 in of rain and snow over 9.1 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 30% and peaks near 32% on the wettest days, and about 4 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
13211
23212
33212
43212
53113
63113
73113
83113
93013
103013
113013
122914
132914
142914
153014
163014
173014
182914
192914
202914
212914
222914
232814
242814
252815
262815
272815
282915
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 (%)Comfortable (%)
1991
2991
3991
4991
5991
6991
7991
8991
9991
10991
111000
121000
131000
141000
151000
161000
171000
181000
191000
201000
211000
221000
231000
241000
251000
261000
271000
281000
291000
301000
311000

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
210light breeze
310light 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
2310light breeze
2410light breeze
2510light breeze
2610light breeze
2710light breeze
2810light breeze
2910light breeze
3010light breeze
3110light breeze

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 12 min at the start of December to 9 hours by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over December. Sunrise moves from 7:02 AM to 7:21 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)
19.27:024:16
29.27:034:15
39.27:044:15
49.27:054:15
59.17:064:15
69.17:074:15
79.17:084:15
89.17:094:15
99.17:104:15
109.17:114:15
119.17:114:15
129.07:124:15
139.07:134:15
149.07:144:15
159.07:144:16
169.07:154:16
179.07:164:16
189.07:164:17
199.07:174:17
209.07:174:17
219.07:184:18
229.07:184:18
239.07:194:19
249.07:194:19
259.07:204:20
269.07:204:20
279.07:204:21
289.07:214:22
299.07:214:22
309.07:214:23
319.07:214:24

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.6 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.6 kWh/m² to a high of 6.59 kWh/m² in June across the year — December's 1.6 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.7Dim
21.7Dim
31.7Dim
41.7Dim
51.7Dim
61.6Dim
71.6Dim
81.6Dim
91.6Dim
101.6Dim
111.6Dim
121.6Dim
131.6Dim
141.6Dim
151.6Dim
161.6Dim
171.6Dim
181.6Dim
191.6Dim
201.6Dim
211.6Dim
221.6Dim
231.6Dim
241.6Dim
251.6Dim
261.6Dim
271.6Dim
281.6Dim
291.6Dim
301.6Dim
311.6Dim
Planning a trip in December

Is December a good time to visit Merrillville?

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 Merrillville.

What to pack for Merrillville in December

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

In December, Merrillville sees daytime highs around 37°F and nights near 26°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 Merrillville 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 10 mi away) is warmest in August at about 73°F and coldest in February near 35°F.

It's comfortable for a long swim from Jul 10 to Sep 16 — about 2.3 months when the water holds above 68°F.

30°40°50°60°70°80°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°F)Comfort
Jan38Bracing
Feb35Bracing
Mar35Bracing
Apr39Bracing
May46Bracing
Jun59Cool
Jul70Refreshing
Aug73Refreshing
Sep68Refreshing
Oct58Bracing
Nov49Bracing
Dec42Bracing

UV index in Merrillville 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 Merrillville 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.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 21UV 9Dec 22UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May7Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov2Moderate
Dec2Low

Air quality in Merrillville 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 Merrillville is worst in July — around 17 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (October, 8 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1516 µg/m³Oct 228 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb13Moderate
Mar14Moderate
Apr13Moderate
May15Moderate
Jun15Moderate
Jul17Moderate
Aug15Moderate
Sep11Good
Oct8Good
Nov8Good
Dec9Good
Location & terrain

Where is Merrillville?

Merrillville sits at 41.5°N, 87.3°W, 656 ft above sea level, in United States. The nearest listed city is Crown Point, 5.0 mi away.

Topography around Merrillville

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

Within 2 miles, the terrain around Merrillville has only modest variations in elevation — a maximum elevation change of 131 ft around an average of 663 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 305 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 673 ft.

The land around Merrillville is covered by trees (34%), artificial surfaces (30%) and grassland (22%) within 2 miles, trees (39%), grassland (20%) and cropland (20%) within 10 miles, and cropland (42%) and water (22%) within 50 miles.

2 miles
131 ft
10 miles
305 ft
50 miles
673 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
December weather nearby: Crown Point 5.0 mi · Hobart 5.6 mi · Griffith 5.6 mi · Schererville 6.2 mi · Gary 7.5 mi · Highland 8.1 mi · Dyer 9.9 mi · Portage 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 Merrillville (41.4828°, -87.3328°, elevation 656 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).