Portsmouth weather in May

In May, Portsmouth sees average daytime highs of 60°F and overnight lows near 49°F, with 3.3 in of rain across 10.5 wet days and about 14.4 hours of daylight. It is the 5th-warmest and 10th-wettest month of the year here.

Highs climb over the month, from about 56°F in the first days to 64°F by the end. The sky is clear or mostly clear about 24% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 54 min at the start of May to 14 h 54 min by month's end. Set against the rest of the year, May is Portsmouth's 12th-clearest and 8th-windiest month. For the whole year in context, see Portsmouth's year-round climate.

Daytime high
60°
5th warmest
Overnight low
49°
8th coldest
Rainfall
3.3 in
10.5 wet days
Daylight
14 h 30 min
4:25 AM – 6:53 PM
Cloud cover
65%
12th clearest
Wind
9 mph
8th windiest
Solar energy
5.65 kWh/m²
Travel score
4.7
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 May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 56°F in the first days to 64°F by the end.

A typical May day in Portsmouth reaches about 60°F in the afternoon and slips back to 49°F overnight — a 11°F spread between the day's warmth and the night's chill. On most days the high lands between 52°F and 70°F. Set against its neighbours, May runs about 9°F warmer than April and about 9°F cooler than June.

30°40°50°60°70°80°151015202531
Avg high (°F)Avg low (°F)
15645
25645
35645
45646
55746
65746
75746
85847
95847
105847
115847
125948
135948
145948
156048
166049
176049
186149
196150
206150
216250
226251
236251
246351
256352
266352
276452
286453
296453
306453
316554

How May really feels in Portsmouth

Once humidity and wind are folded in, May averages 0 days that feel above 90°F and 0 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
0
wind chill below the day's low

May sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Portsmouth weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 10th-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 May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 24% of the time in May, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 16% of May, with mostly cloudy or overcast conditions the remaining 60%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14258
24159
34258
44159
54060
64060
73961
83961
93961
103961
113961
123961
133961
143862
153961
163961
173961
184060
194060
204060
214159
224159
234159
244159
254258
264258
274258
284357
294258
304159
314258

Chance of precipitation in May

Any precipitation

Portsmouth gets around 3.3 in of rain over 10.5 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 34% and peaks near 36% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
136
236
336
435
535
635
734
834
934
1034
1134
1234
1334
1434
1533
1633
1733
1833
1933
2033
2133
2233
2333
2433
2533
2633
2733
2834
2934
3034
3134

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, May lands in the dry band about 90% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)
198200
298200
397300
497300
597300
697300
797300
897300
996400
1096400
1196400
1296400
1395410
1495410
1594510
1694510
1794510
1892620
1991720
2090730
2189830
2287940
23861040
24841150
25831250
26811360
27791470
28781570
29761680
30751681
31731791

Wind in May

Winds average 9 mph in May.

Across May, daily wind ranges from about 9 mph on the calmest days to 9 mph at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (mph)Feels
19light breeze
29light breeze
39light breeze
49light breeze
59light breeze
69light breeze
79light breeze
89light breeze
99light breeze
109light breeze
119light breeze
129light breeze
139light breeze
149light breeze
159light breeze
169light breeze
179light breeze
189light breeze
199light breeze
209light breeze
219light breeze
229light breeze
239light breeze
249light breeze
259light breeze
269light breeze
279light breeze
289light breeze
299light breeze
309light breeze
319light breeze

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 54 min at the start of May to 14 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 60 minutes over May. Sunrise moves from 4:44 AM to 4:13 AM, and sunset from 6:36 PM to 7:08 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.94:446:36
213.94:436:37
314.04:416:39
414.04:406:40
514.04:396:41
614.14:376:42
714.14:366:43
814.24:356:44
914.24:336:45
1014.24:326:47
1114.34:316:48
1214.34:306:49
1314.44:296:50
1414.44:286:51
1514.44:266:52
1614.54:256:53
1714.54:246:54
1814.54:236:55
1914.64:226:56
2014.64:216:57
2114.64:206:58
2214.74:206:59
2314.74:197:00
2414.74:187:01
2514.84:177:02
2614.84:167:03
2714.84:167:04
2814.84:157:05
2914.94:147:06
3014.94:147:07
3114.94:137:08

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.65 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 — May's 5.65 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.3Bright
45.4Bright
55.4Bright
65.4Bright
75.4Bright
85.4Bright
95.5Bright
105.5Bright
115.5Bright
125.5Bright
135.6Bright
145.6Bright
155.6Bright
165.6Bright
175.7Bright
185.7Bright
195.7Bright
205.7Bright
215.8Bright
225.8Bright
235.8Bright
245.8Bright
255.8Bright
265.8Bright
275.9Bright
285.9Bright
295.9Bright
305.9Bright
315.9Bright
Planning a trip in May

Hazard calendar for Portsmouth

In seasonPeak

None of Portsmouth's seasonal hazards are active in May. 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 May a good time to visit Portsmouth?

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

4.7
Sightseeing
5th-best month of the year
0.7
Beach & pool
5th-best month of the year

May is a reasonable time to visit Portsmouth for sightseeing.

What to pack for Portsmouth in May

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

In May, Portsmouth sees daytime highs around 60°F and nights near 49°F. Worth packing: a warm layer, rain gear and sun protection. About 11 days see rain.

a warm layerrain gearsun protection

Sea temperature near Portsmouth in May

The nearest coast averages about 49°F in May — 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 May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 7 — enough to warrant sun protection. 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
May 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).