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Best time to visit Portsmouth, NH, USA

Our verdict

The best time to visit Portsmouth is March-April

Portsmouth can be visited year-round, but based on the ideal climate conditions, cost of travel, and avoiding peak holiday periods, March-April is the best time to go.

During the warmer months, temperatures in Portsmouth can rise to a maximum of 32℃ (89℉). In the winter months, it can get down to as low as -2℃ (29℉) at night.

If you want to get the most out of your time visiting Portsmouth, or you’re just afraid of the dark, the days in July are usually the longest between sunrise and sunset. On average it rains the most days in September, making it the wettest month of the year. Although it’s the wet season, it can often rain a little bit during the day or evening but have fine weather for a majority of the day too, so don’t let this put you off.

To learn everything you need to know (and none of the stuff you don’t) about when to visit Portsmouth, keep reading below. Plus, you’ll find tools to help you get the best deals on travel and hotels too!

Warmest month

July

Least rainfall

November

Most daylight

July

Portsmouth seasons

Before you continue, it’s important to know when the seasons are in Portsmouth as they might be different to yours depending on where in the world you’re travelling from. Portsmouth is in the Northern Hemisphere, so the seasons fall during these months:

SeasonMonths
Summer June to August
Autumn/fall September to November
Winter December to February
Spring March to May

Average temperatures in Portsmouth

If the temperature is a big factor for you to help you decide when to visit, the chart below shows the average minimum and maximum temperatures in Portsmouth for each month side-by-side so you can easily see the difference in weather throughout the year. To see the temperatures in both Celsius (°C) and Fahrenheit (°F), hover or tap the shaded boxes on the graph.

Portsmouth climate by month

If you already have a rough idea about which months you might want to travel, the section below shows a detailed breakdown of the climate in Portsmouth for each month so you can see if it all suits your wants and needs. Scroll down, or use the quick menu below to jump to your preferred month.

Jump to:

JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC

Portsmouth in January

  • Average temperature: 5℃ (41℉)
  • Average high temperature: 8℃ (46℉)
  • Average low temperature: 2℃ (35℉)
  • Average humidity: 75%
  • Average sunny days: 19 days
  • Average rainfall: 33mm (1") over 8 days
  • Average snow days: 2 days
19 days
of pure sunshine
8 days
of showers or rain

What to pack: If you’re heading to Portsmouth in January, make sure you pack a thick snow/winter jacket, thermals and some extra layers as it's always very cold.


Portsmouth in February

  • Average temperature: 6℃ (43℉)
  • Average high temperature: 10℃ (49℉)
  • Average low temperature: 3℃ (37℉)
  • Average humidity: 75%
  • Average sunny days: 16 days
  • Average rainfall: 36mm (1") over 10 days
  • Average snow days: 2 days
16 days
of pure sunshine
10 days
of showers or rain

What to pack: If you’re heading to Portsmouth in February, make sure you pack a thick snow/winter jacket, thermals and some extra layers as it's always very cold.


Portsmouth in March

  • Average temperature: 9℃ (49℉)
  • Average high temperature: 12℃ (54℉)
  • Average low temperature: 6℃ (43℉)
  • Average humidity: 75%
  • Average sunny days: 15 days
  • Average rainfall: 34mm (1") over 14 days
15 days
of pure sunshine
14 days
of showers or rain

What to pack: If you’re heading to Portsmouth in March, make sure you pack a warm jacket or coat.


Portsmouth in April

  • Average temperature: 15℃ (59℉)
  • Average high temperature: 18℃ (65℉)
  • Average low temperature: 11℃ (52℉)
  • Average humidity: 75%
  • Average sunny days: 14 days
  • Average rainfall: 37mm (1") over 13 days
14 days
of pure sunshine
13 days
of showers or rain

What to pack: If you’re heading to Portsmouth in April, make sure you pack a warm jacket or coat.


Portsmouth in May

  • Average temperature: 20℃ (68℉)
  • Average high temperature: 23℃ (74℉)
  • Average low temperature: 16℃ (61℉)
  • Average humidity: 78%
  • Average sunny days: 12 days
  • Average rainfall: 48mm (2") over 16 days
12 days
of pure sunshine
16 days
of showers or rain

What to pack: If you’re heading to Portsmouth in May, make sure you pack t-shirts for the daytime and maybe a light jumper for the evenings as it cools down a bit.


Portsmouth in June

  • Average temperature: 24℃ (76℉)
  • Average high temperature: 28℃ (82℉)
  • Average low temperature: 21℃ (69℉)
  • Average humidity: 76%
  • Average sunny days: 11 days
  • Average rainfall: 42mm (2") over 14 days
11 days
of pure sunshine
14 days
of showers or rain

What to pack: If you’re heading to Portsmouth in June, make sure you pack t-shirts and light clothing.


Portsmouth in July

  • Average temperature: 26℃ (80℉)
  • Average high temperature: 30℃ (86℉)
  • Average low temperature: 23℃ (73℉)
  • Average humidity: 75%
  • Average sunny days: 12 days
  • Average rainfall: 54mm (2") over 17 days
12 days
of pure sunshine
17 days
of showers or rain

What to pack: If you’re heading to Portsmouth in July, make sure you pack t-shirts and light clothing.


Portsmouth in August

  • Average temperature: 26℃ (78℉)
  • Average high temperature: 29℃ (85℉)
  • Average low temperature: 23℃ (73℉)
  • Average humidity: 75%
  • Average sunny days: 11 days
  • Average rainfall: 53mm (2") over 16 days
11 days
of pure sunshine
16 days
of showers or rain

What to pack: If you’re heading to Portsmouth in August, make sure you pack t-shirts and light clothing.


Portsmouth in September

  • Average temperature: 23℃ (73℉)
  • Average high temperature: 26℃ (79℉)
  • Average low temperature: 20℃ (68℉)
  • Average humidity: 76%
  • Average sunny days: 14 days
  • Average rainfall: 58mm (2") over 13 days
14 days
of pure sunshine
13 days
of showers or rain

What to pack: If you’re heading to Portsmouth in September, make sure you pack t-shirts and light clothing.

Portsmouth in October

  • Average temperature: 18℃ (64℉)
  • Average high temperature: 21℃ (70℉)
  • Average low temperature: 15℃ (58℉)
  • Average humidity: 75%
  • Average sunny days: 19 days
  • Average rainfall: 40mm (2") over 10 days
19 days
of pure sunshine
10 days
of showers or rain

What to pack: If you’re heading to Portsmouth in October, make sure you pack a light jumper or hoodie for the evenings and some light clothes for the daytime.


Portsmouth in November

  • Average temperature: 12℃ (53℉)
  • Average high temperature: 15℃ (58℉)
  • Average low temperature: 8℃ (47℉)
  • Average humidity: 74%
  • Average sunny days: 19 days
  • Average rainfall: 28mm (1") over 8 days
19 days
of pure sunshine
8 days
of showers or rain

What to pack: If you’re heading to Portsmouth in November, make sure you pack a warm jacket or coat.


Portsmouth in December

  • Average temperature: 8℃ (46℉)
  • Average high temperature: 11℃ (51℉)
  • Average low temperature: 5℃ (41℉)
  • Average humidity: 77%
  • Average sunny days: 19 days
  • Average rainfall: 37mm (1") over 11 days
  • Average snow days: 1 days
19 days
of pure sunshine
11 days
of showers or rain

What to pack: If you’re heading to Portsmouth in December, make sure you pack a thick snow/winter jacket, thermals and some extra layers as it's always very cold.


Top FAQs

The hottest month of the year in Portsmouth is usually July, where temperatures tend to rise to around 30℃ (86℉) in the middle of the day or early afternoon.
The month with the least amount of rain in Portsmouth is generally around November. The dry season often coincides with cooler weather, so you should check the temperatures in November first to make sure it’s still a good time to go.
The rainiest time of year in Portsmouth is generally around September, although the wetter season can sometimes extend a few months either side of September too.
If you want to get the most out of your time visiting Portsmouth, or if you're just afraid of the dark, the days in July are usually the longest between sunrise and sunset.

Portsmouth map