Portsmouth
New Hampshire, USA
Long-term weather forecast
Long-term weather forecast

Monthly weather forecast and climate
Portsmouth, NH

Bright neon lights and buildings next to the very calm waters of the iconic Piscataqua River in Portsmouth, New Hampshire, the clear dusk sky in close up view
Bright neon lights and buildings next to the very calm waters of the iconic Piscataqua River in Portsmouth, New Hampshire, the clear dusk sky in close up view
January, the same as December, is a wintry winter month in Portsmouth, New Hampshire, with average temperature fluctuating between 16°F (-8.9°C) and 32°F (0°C). The coldest months are January and February, with an average high-temperature of 32°F (0°C). Weather in January »
February, the last month of the winter, in Portsmouth, is another cold month, with temperature in the range of an average high of 32°F (0°C) and an average low of 18°F (-7.8°C). The coldest months are January and February, with an average high-temperature of 32°F (0°C). Weather in February »

March, the first month of the spring, in Portsmouth, is still a cold month, with temperature in the range of an average high of 41°F (5°C) and an average low of 27°F (-2.8°C). In Portsmouth, the average high-temperature increases, from a wintry 32°F (0°C) in February, to a still cold 41°F (5°C). Weather in March »

April in Portsmouth, New Hampshire, is a fresh spring month, with temperature in the range of an average low of 36°F (2.2°C) and an average high of 52°F (11.1°C). In Portsmouth, the average high-temperature in April rises, from a wintry 41°F (5°C) in March, to a cool 52°F (11.1°C). Weather in April »

The last month of the spring, May, is a comfortable month in Portsmouth, New Hampshire, with average temperature ranging between max 64°F (17.8°C) and min 45°F (7.2°C). In Portsmouth, the average high-temperature in May rises, from a cool 52°F (11.1°C) in April, to an enjoyable 64°F (17.8°C). Weather in May »

The first month of the summer, June, is a pleasant month in Portsmouth, New Hampshire, with average temperature fluctuating between 55°F (12.8°C) and 73°F (22.8°C). In June, the average high-temperature rises, from an enjoyable 64°F (17.8°C) in May, to a pleasant 73°F (22.8°C). Weather in June »

July is a moderately hot summer month in Portsmouth, New Hampshire, with average temperature fluctuating between 61°F (16.1°C) and 79°F (26.1°C). With an average high-temperature of 79°F (26.1°C) and an average low-temperature of 61°F (16.1°C), July is the warmest month. Weather in July »

August, the last month of the summer, in Portsmouth, is also a moderately hot month, with temperature in the range of an average low of 59°F (15°C) and an average high of 77°F (25°C). In Portsmouth, the average high-temperature is essentially the same as in July - a still warm 77°F (25°C). Weather in August »

The first month of the autumn, September, is still a pleasant month in Portsmouth, New Hampshire, with average temperature ranging between min 52°F (11.1°C) and max 70°F (21.1°C). In September, the average high-temperature marginally drops, from a warm 77°F (25°C) in August, to an agreeable 70°F (21.1°C). Weather in September »

October, the same as September, in Portsmouth, New Hampshire, is a moderate autumn month, with temperature in the range of an average low of 41°F (5°C) and an average high of 59°F (15°C). In Portsmouth, the average high-temperature in October decreases, from a pleasant 70°F (21.1°C) in September, to a mild 59°F (15°C). Weather in October »

The last month of the autumn, November, is another chilly month in Portsmouth, New Hampshire, with average temperature ranging between min 34°F (1.1°C) and max 48°F (8.9°C). In Portsmouth, the average high-temperature drops, from a moderate 59°F (15°C) in October, to a frosty 48°F (8.9°C). Weather in November »

The first month of the winter, December, is still a cold month in Portsmouth, New Hampshire, with average temperature ranging between max 34°F (1.1°C) and min 21°F (-6.1°C). In December, the average high-temperature decreases, from a frosty 48°F (8.9°C) in November, to a cold 34°F (1.1°C). Weather in December »

What is the coldest month in Portsmouth?

January and February, with an average high-temperature of 32°F (0°C), are the coldest months in Portsmouth, New Hampshire.

How many days does it rain in Portsmouth?

Throughout the year, in Portsmouth, there are 125 rainfall days, and 42.4" (1078mm) of precipitation is accumulated.

What is the month with the least sunshine in Portsmouth?

January, November and December, with an average of 5h of sunshine, are months with the least sunshine in Portsmouth, New Hampshire.

What is the month with the lowest UV index in Portsmouth?

January and December, with an average maximum UV index of 1, are months with the lowest UV index in Portsmouth, New Hampshire.

What is the month with the coldest ocean in Portsmouth?

The month with the coldest seawater in Portsmouth, New Hampshire, is March, with an average ocean temperature of 38.5°F (3.6°C). For swimming, this is considered very dangerous and immediately life-threatening. Total loss of breathing control instantly occurs, and clear thinking becomes almost impossible. A specialized swimsuit is obligatory to minimize thermal loss.

When are the longest days in Portsmouth?

The month with the longest days in Portsmouth, New Hampshire, is June, with an average of 15.3h of daylight.

What are the months with the most sunshine in Portsmouth?

Months with the most sunshine are June through August, with an average of 9h of sunshine.

What is the month with the highest UV index in Portsmouth?

June and July, with an average maximum UV index of 8, are months with the highest UV index.

What is the warmest month in Portsmouth?

The warmest month in Portsmouth is July, with an average high-temperature of 79°F (26.1°C) and an average low-temperature of 61°F (16.1°C).

What is the driest month in Portsmouth?

August is the month with the least rainfall. Rain falls for 10 days and accumulates 2.8" (70mm) of precipitation.

When is the ocean warmest in Portsmouth?

August is the month with the warmest seawater in Portsmouth, New Hampshire, with an average ocean temperature of 65.7°F (18.7°C). For most, swimming in 65.7°F (18.7°C) is not an enjoyable activity. Furthermore, controlling your breathing becomes progressively more difficult as the water temperature decreases from 69.8°F (21°C) to 59°F (15°C).

What is the rainiest month in Portsmouth?

November is the month with the most rainfall in Portsmouth. Rain falls for 11 days and accumulates 4.9" (125mm) of precipitation.

What is the month with the shortest days in Portsmouth?

The month with the shortest days in Portsmouth, New Hampshire, is December, with an average of 9.1h of daylight.
Average rainfall - Portsmouth, NH
Average rainfall days - Portsmouth, NH

Months with the highest number of rainy days are May and December (12 days).
The month with the lowest number of rainy days is September (8 days).

Average sea temperature - Portsmouth, NH

The best month for swimming (with the highest average sea temperature) is August (65.6°F).
The coldest month (with the lowest average sea temperature) is March (38.5°F).

Average daylight / Average sunshine - Portsmouth, NH