Portsmouth weather in January

In January, Portsmouth sees average daytime highs of 34°F and overnight lows near 22°F, with 3.6 in of precipitation across 9.9 wet days and about 9.2 hours of daylight. It is the 12th-warmest and 6th-wettest month of the year here.

Day-to-day highs hold fairly steady near 34°F through the month. The sky is clear or mostly clear about 35% of the time in January, and the air most often feels dry.

Daylight stretches from about 8 h 54 min at the start of January to 9 h 36 min by month's end. Set against the rest of the year, January is Portsmouth's 5th-clearest and 1st-windiest month. For the whole year in context, see Portsmouth's year-round climate.

Daytime high
34°
12th warmest
Overnight low
22°
1st coldest
Precipitation
3.6 in
9.9 wet days
Daylight
9 h 06 min
7:18 AM – 4:27 PM
Cloud cover
57%
5th clearest
Wind
11 mph
1st windiest
Solar energy
1.91 kWh/m²
Travel score
0.0
out of 10

Portsmouth is city in Rockingham County, New Hampshire, United States.

Density
494/km²
people per km²
Founded
1630

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in January

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 34°F through the month.

A typical January day in Portsmouth reaches about 34°F in the afternoon and slips back to 22°F overnight — a 12°F spread between the day's warmth and the night's chill. On most days the high lands between 21°F and 46°F. Set against its neighbours, January runs about 5°F cooler than December and about 1°F cooler than February.

10°20°30°40°50°151015202531
Avg high (°F)Avg low (°F)
13524
23524
33524
43524
53524
63523
73523
83423
93423
103422
113422
123422
133422
143322
153322
163321
173321
183321
193321
203321
213321
223321
233321
243321
253321
263321
273321
283321
293321
303321
313321

How January really feels in Portsmouth

Once humidity and wind are folded in, January 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
31 feel bitter (≤ 14°F)

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

Portsmouth weather by month

How January compares with the rest of the year at a glance. January is the 12th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan34° / 22°3.69.96.79.20.0
Feb35° / 23°3.49.1610.20.0
Mar41° / 30°4.511.25.211.60.2
Apr51° / 40°4.210.61.313.12.4
May60° / 49°3.310.5014.44.7
Jun69° / 58°3.610.6015.16.3
Jul75° / 65°3.110.6014.96.9
Aug74° / 64°3.28.8013.87.2
Sep68° / 57°3.48.5012.36.6
Oct58° / 47°4.49.90.210.84.5
Nov48° / 37°3.89.71.29.51.8
Dec39° / 28°4.610.84.98.90.1

Cloud cover in January

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 35% of the time in January.

Beyond those clear spells, partly cloudy skies cover about 17% of January, with mostly cloudy or overcast conditions the remaining 48%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15050
25050
35050
45050
55050
65050
75050
84951
95050
105050
115050
125050
135050
145149
155149
165149
175149
185248
195248
205248
215347
225347
235347
245446
255446
265446
275347
285446
295446
305446
315446

Chance of precipitation in January

Any precipitationSnow

Portsmouth gets around 3.6 in of rain and snow over 9.9 wet days in January. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 32% and peaks near 34% on the wettest days, and about 7 days bring snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
13419
23419
33420
43420
53421
63421
73421
83422
93422
103422
113423
123423
133424
143424
153324
163324
173324
183223
193223
203223
213123
223122
233022
243022
253021
263021
272921
282921
292920
302920
312920

Humidity in January

DryComfortableHumidMuggyOppressiveMiserable

Most of January feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, January 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 January

Winds average 11 mph in January, the windiest month of the year.

Across January, daily wind ranges from about 11 mph on the calmest days to 12 mph at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (mph)Feels
111light breeze
211light breeze
311light breeze
411light breeze
511light breeze
611light breeze
711light breeze
811light breeze
912light breeze
1012light breeze
1112light breeze
1212light breeze
1312light breeze
1412light breeze
1512light breeze
1612light breeze
1712light breeze
1812light breeze
1912light breeze
2012light breeze
2111light breeze
2211light breeze
2311light breeze
2411light breeze
2511light breeze
2611light breeze
2711light breeze
2811light breeze
2911light breeze
3011light breeze
3111light breeze

Sunrise & sunset in January

DaylightNight

Daylight runs from about 8 h 54 min at the start of January to 9 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 42 minutes over January. Sunrise moves from 7:20 AM to 7:08 AM, and sunset from 4:12 PM to 4:45 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
18.97:204:12
28.97:204:13
38.97:204:14
48.97:204:15
58.97:204:16
68.97:204:16
79.07:204:17
89.07:204:18
99.07:204:19
109.07:204:20
119.07:204:21
129.17:194:22
139.17:194:23
149.17:194:25
159.17:184:26
169.17:184:27
179.27:174:28
189.27:174:29
199.27:164:30
209.37:164:31
219.37:154:33
229.37:154:34
239.47:144:35
249.47:134:36
259.47:134:38
269.47:124:39
279.57:114:40
289.57:104:41
299.67:094:43
309.67:084:44
319.67:084:45

Solar energy in January

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in January, about 1.91 kWh/m².

For context, solar energy here swings from a low near 1.54 kWh/m² to a high of 6.11 kWh/m² in July across the year — January's 1.91 kWh/m² sits near the bottom.

0123151015202531
Solar energy (kWh/m²)Level
11.6Dim
21.6Dim
31.6Dim
41.6Dim
51.7Dim
61.7Dim
71.7Dim
81.7Dim
91.7Dim
101.7Dim
111.8Dim
121.8Dim
131.8Dim
141.8Dim
151.8Dim
161.9Dim
171.9Dim
181.9Dim
192.0Dim
202.0Dim
212.0Moderate
222.1Moderate
232.1Moderate
242.1Moderate
252.2Moderate
262.2Moderate
272.2Moderate
282.3Moderate
292.3Moderate
302.3Moderate
312.4Moderate
Planning a trip in January

Hazard calendar for Portsmouth

In seasonPeak

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

Portsmouth 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 January a good time to visit Portsmouth?

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

0.0
Sightseeing
11th-best month of the year
0.0
Beach & pool
8th-best month of the year

January is a weaker month for outdoor sightseeing in Portsmouth.

What to pack for Portsmouth in January

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

In January, Portsmouth sees daytime highs around 34°F and nights near 22°F. Pack a warm layer and a heavy coat. Worth having: rain gear. About 10 days see rain.

a warm layera heavy coatrain gear

Sea temperature near Portsmouth in January

The nearest coast averages about 42°F in January — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in August at about 65°F and coldest in March near 38°F.

The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.

40°50°60°70°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshing
Sea temperature (°F)Comfort
Jan42Bracing
Feb39Bracing
Mar38Bracing
Apr42Bracing
May49Bracing
Jun57Bracing
Jul63Cool
Aug65Cool
Sep62Cool
Oct55Bracing
Nov49Bracing
Dec45Bracing

UV index in Portsmouth in January

LowModerateHighVery highExtreme

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

Under clear skies, the midday UV index in Portsmouth peaks around July 10 at about 7 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 23 at about 1 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighHighModerateModerateLowJul 10UV 7Dec 23UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar4Moderate
Apr5High
May7High
Jun7High
Jul7Very high
Aug4Moderate
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low
Location & terrain

Where is Portsmouth?

Portsmouth sits at 43.1°N, 70.8°W, 20 ft above sea level, in United States. The nearest listed city is Dover, 9.9 mi away.

Topography around Portsmouth

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

Within 2 miles, the terrain around Portsmouth has only modest variations in elevation — a maximum elevation change of 161 ft around an average of 39 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 430 ft; within 50 miles, large variations in elevation — a maximum elevation change of 2,454 ft.

The land around Portsmouth is covered by trees (45%), water (22%) and artificial surfaces (21%) within 2 miles, trees (49%) and water (36%) within 10 miles, and trees (61%) and water (32%) within 50 miles.

2 miles
161 ft
10 miles
430 ft
50 miles
2,454 ft
treesgrasslandartificial surfaceswaterwetland
January weather nearby: Dover 9.9 mi · Amesbury 17 mi · Rochester 19 mi · Newburyport 19 mi · Sanford 25 mi · Haverhill 26 mi · Salem 30 mi · Derry Village 31 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 Portsmouth (43.077°, -70.7577°, elevation 20 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. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).