Hillsborough weather in December

In December, Hillsborough sees average daytime highs of 44°F and overnight lows near 30°F, with 4.0 in of precipitation across 9.6 wet days and about 9.2 hours of daylight. It is the 10th-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 47°F in the first days to 41°F by the end. The sky is clear or mostly clear about 30% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 18 min at the start of December to 9 h 06 min by month's end. Set against the rest of the year, December is Hillsborough's 7th-clearest and 4th-windiest month. For the whole year in context, see Hillsborough's year-round climate.

Daytime high
44°
10th warmest
Overnight low
30°
3rd coldest
Precipitation
4.0 in
9.6 wet days
Daylight
9 h 06 min
7:21 AM – 4:28 PM
Cloud cover
61%
7th clearest
Wind
7 mph
4th windiest
Solar energy
1.77 kWh/m²
Travel score
0.6
out of 10

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 47°F in the first days to 41°F by the end.

A typical December day in Hillsborough reaches about 44°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 32°F and 56°F. Set against its neighbours, December runs about 10°F cooler than November and about 5°F warmer than January.

20°40°60°151015202531
Avg high (°F)Avg low (°F)
14834
24734
34733
44733
54633
64633
74532
84532
94532
104431
114431
124431
134431
144331
154330
164330
174330
184330
194230
204230
214229
224229
234229
244229
254229
264229
274128
284128
294128
304128
314128

How December really feels in Hillsborough

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.

Hillsborough weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan39° / 25°3.39.14.39.40.0
Feb42° / 26°3.093.710.40.3
Mar50° / 33°4.210.63.311.72.2
Apr62° / 43°3.710.70.4135.0
May71° / 53°3.611.7014.26.3
Jun81° / 62°4.311.5014.86.0
Jul85° / 68°4.211.3014.65.0
Aug83° / 66°4.010.4013.65.8
Sep76° / 59°4.19.2012.36.9
Oct65° / 47°3.78.60.110.96.0
Nov53° / 38°3.07.90.59.73.2
Dec44° / 30°4.09.62.69.20.6

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 30% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 15% of December, with mostly cloudy or overcast conditions the remaining 55%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14753
24654
34654
44555
54456
64456
74456
84357
94357
104258
114258
124258
134258
144258
154258
164357
174357
184357
194456
204456
214654
224753
234753
244654
254654
264753
274753
284753
294753
304654
314654

Chance of precipitation in December

Any precipitationSnow

Hillsborough gets around 4.0 in of rain and snow over 9.6 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 31% and peaks near 33% on the wettest days, and about 3 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
1305
2306
3316
4317
5327
6328
7338
8339
9339
10339
113310
123310
133210
143210
153210
16319
17319
18309
19309
20299
21298
22298
23288
24288
25288
26288
27298
28298
29299
30299
313010

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
4991
5991
6991
7991
8991
9991
10991
11991
12991
13991
14991
15991
16991
17991
18991
19991
20991
21991
22991
23991
24991
25991
26991
27991
28991
291000
301000
311000

Wind in December

Winds average 7 mph in December.

Across December, daily wind ranges from about 7 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm
317calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 18 min at the start of December to 9 h 06 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 7:09 AM to 7:27 AM, and sunset from 4:28 PM to 4:36 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.37:094:28
29.37:104:28
39.37:114:28
49.37:114:27
59.27:124:27
69.27:134:27
79.27:144:27
89.27:154:27
99.27:164:27
109.27:174:27
119.27:174:27
129.27:184:27
139.17:194:28
149.17:204:28
159.17:204:28
169.17:214:28
179.17:224:29
189.17:224:29
199.17:234:29
209.17:234:30
219.17:244:30
229.17:244:31
239.17:254:31
249.17:254:32
259.17:264:32
269.17:264:33
279.17:264:33
289.17:274:34
299.17:274:35
309.17:274:35
319.17:274:36

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.77 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.77 kWh/m² to a high of 5.99 kWh/m² in June across the year — December's 1.77 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.9Dim
21.9Dim
31.9Dim
41.8Dim
51.8Dim
61.8Dim
71.8Dim
81.8Dim
91.8Dim
101.8Dim
111.8Dim
121.7Dim
131.7Dim
141.7Dim
151.7Dim
161.7Dim
171.7Dim
181.7Dim
191.7Dim
201.8Dim
211.8Dim
221.8Dim
231.8Dim
241.8Dim
251.8Dim
261.8Dim
271.8Dim
281.8Dim
291.8Dim
301.8Dim
311.8Dim
Planning a trip in December

Hazard calendar for Hillsborough

In seasonPeak

None of Hillsborough's seasonal hazards are active in December. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

Hillsborough sits in the Atlantic hurricane belt; the season peaks August–October.

Atlantic hurricane
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is December a good time to visit Hillsborough?

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

0.6
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 Hillsborough.

What to pack for Hillsborough in December

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

In December, Hillsborough sees daytime highs around 44°F and nights near 30°F. Pack a warm layer. Worth having: a heavy coat and rain gear. About 10 days see rain.

a warm layera heavy coatrain gear

Sea temperature near Hillsborough in December

The nearest coast averages about 49°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 40 mi away) is warmest in August at about 74°F and coldest in February near 40°F.

It's comfortable for a long swim from Jun 30 to Sep 27 — about 3 months when the water holds above 68°F.

40°50°60°70°80°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°F)Comfort
Jan43Bracing
Feb40Bracing
Mar41Bracing
Apr46Bracing
May55Bracing
Jun65Cool
Jul72Refreshing
Aug74Refreshing
Sep71Refreshing
Oct64Cool
Nov55Bracing
Dec49Bracing

UV index in Hillsborough 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 Hillsborough peaks around July 11 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 1 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateLowJul 11UV 8Dec 21UV 1
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun8Very high
Jul8Very high
Aug6High
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Hillsborough 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 Hillsborough is worst in July — around 18 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (November, 9 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1518 µg/m³Nov 149 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb13Moderate
Mar14Moderate
Apr14Moderate
May16Moderate
Jun17Moderate
Jul18Moderate
Aug15Moderate
Sep13Moderate
Oct10Good
Nov9Good
Dec10Good
Location & terrain

Where is Hillsborough?

Hillsborough sits at 40.5°N, 74.6°W, 85 ft above sea level, in United States. The nearest listed city is Somerset, 7.5 mi away.

Topography around Hillsborough

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

Within 2 miles, the terrain around Hillsborough has only modest variations in elevation — a maximum elevation change of 161 ft around an average of 105 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 673 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,962 ft.

The land around Hillsborough is covered by trees (56%) and grassland (29%) within 2 miles, trees (64%) and grassland (22%) within 10 miles, and trees (61%) within 50 miles.

2 miles
161 ft
10 miles
673 ft
50 miles
1,962 ft
treesgrasslandcroplandartificial surfaceswater
December weather nearby: Somerset 7.5 mi · North Brunswick 8.1 mi · Bridgewater 8.7 mi · Princeton 9.3 mi · New Brunswick 9.3 mi · Warren Township 11 mi · East Brunswick 12 mi · Edison 12 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 Hillsborough (40.4776°, -74.6268°, elevation 85 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). 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).