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

January 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).

Temperature

The coldest months are January and February, with an average high-temperature of 32°F (0°C).

Rainfall

In Portsmouth, during January, the rain falls for 11 days and regularly aggregates up to 3.4" (87mm) of precipitation. In Portsmouth, during the entire year, the rain falls for 125 days and collects up to 42.4" (1078mm) of precipitation.

Ocean temperature

In Portsmouth, in January, the average water temperature is 41.5°F (5.3°C). Swimming in 41.5°F (5.3°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.

Daylight

In January, the average length of the day in Portsmouth is 9.4h.

Sunshine

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

UV index

Months with the lowest UV index are January and December, with an average maximum UV index of 1. A UV Index value of 2, and less, symbolizes a minimal health hazard from unprotected exposure to the Sun's UV rays for the average person.
The average daily UV index of 1 transform into the following instructions:
For the majority, extended sun exposure is not of great concern. Infants and people with sensitive skin must always be protected. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.

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.

What is the temperature in January in Portsmouth?

In Portsmouth, in January, the average high-temperature is 32°F (0°C), and the average low-temperature is 16°F (-8.9°C).

How much does it rain in Portsmouth in January?

In January, in Portsmouth, the rain falls for 11 days. Throughout January, 3.4" (87mm) of precipitation is accumulated.

What is the ocean temperature in January in Portsmouth?

In Portsmouth, New Hampshire, the average seawater temperature in January is 41.5°F (5.3°C). Swimming in 41.5°F (5.3°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.

How many hours of daylight does Portsmouth have in January?

In Portsmouth, New Hampshire, the average length of the day in January is 9.4h.

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.

How many hours of sunshine does Portsmouth have in January?

In January, the average sunshine is 5h.

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.

What is the UV index intensity in January in Portsmouth?

In January, the average daily maximum UV index is 1. A UV Index value of 2, and less, symbolizes a low health threat from the exposure to the Sun's UV radiation.
Average temperature in January - Portsmouth, NH
  • Average high temperature in January: 32°F

The warmest month (with the highest average high temperature) is July (79°F).
Months with the lowest average high temperature are January and February (32°F).

  • Average low temperature in January: 16°F

The month with the highest average low temperature is July (61°F).
The coldest month (with the lowest average low temperature) is January (16°F).

Average rainfall in January - Portsmouth, NH
  • Average rainfall in January: 3.4"

The wettest month (with the highest rainfall) is November (4.9").
The driest month (with the lowest rainfall) is August (2.8").

Average rainfall days in January - Portsmouth, NH
  • Average rainfall days in January: 11 days

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 in January - Portsmouth, NH
  • Average sea temperature in January: 41.5°F

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 in January / Average sunshine in January - Portsmouth, NH
  • Average daylight in January: 9.4h

The month with the longest days is June (Average daylight: 15.3h).
The month with shortest days is December (Average daylight: 9.1h).

  • Average sunshine in January: 5h

Months with most sunshine are June, July and August (Average sunshine: 9h).
Months with least sunshine are January, November and December (Average sunshine: 5).

Average UV index in January - Portsmouth, NH
  • Average UV index in January: 1

Months with the highest UV index are June and July (UV index 8).
Months with the lowest UV index are January and December (UV index 1).