December weather forecast
Merrimack, NH

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Weather in December

December marks the full arrival of winter in Merrimack with accompanying cold winds. The city is adorned with festive decorations, complementing the beauty of the snow-covered landscapes. A considered viewing reveals the city preparing to welcome the New Year, braving the icy grip of winter. Persistent winter weather conditions even lead to limited outdoor activities and events. During the peak of winter in December, the city witnesses maximum snowfall, reaching up to 2.99" (76mm).

Temperature

The average high-temperature drops in December, from November's chilly 46.6°F (8.1°C) to a cold 36.3°F (2.4°C). An average low-temperature of 25.3°F (-3.7°C) is noted during the nights in December.

Humidity

In December, the average relative humidity is 79%.

Rainfall

In Merrimack, in December, it is raining for 6.3 days, with typically 1.1" (28mm) of accumulated precipitation. Throughout the year, in Merrimack, there are 104.4 rainfall days, and 12.95" (329mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through May, October through December. December is the month with the most snowfall. Snow falls for 4 days and accumulates 2.99" (76mm) of snow.

Daylight

December has the shortest days of the year, with an average of 9h and 6min of daylight.
On the first day of December in Merrimack, sunrise is at 6:57 am and sunset at 4:12 pm. On the last day of the month, sunrise is at 7:16 am and sunset at 4:21 pm EST.

Sunshine

The average sunshine in December in Merrimack is 4.8h.

UV index

January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index value of 2, and less, symbolizes a minimal health vulnerability from unsafe exposure to UV radiation for average individuals.
Note: In December, the maximum UV index of 2 suggests this advice:
Protection from prolonged sun exposure is necessary for babies, children, and individuals with sensitive skin. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection. Heed this! Snow reflection can almost augment the UV radiation of the sun by double.
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Frequently asked questions

How cold is it in Merrimack in December?

In Merrimack, 36.3°F (2.4°C) is the average high-temperature and 25.3°F (-3.7°C) is the average low-temperature during December. In July, the average heat index (a.k.a. 'real feel', 'felt air temperature'), which calculates the temperature value influenced by the moisture in the air, is appraised at 86°F (30°C).

What is the average humidity in December in Merrimack?

In Merrimack, New Hampshire, the average relative humidity in December is 79%.

How many days does it rain in December in Merrimack?

In Merrimack, in December, it is raining for 6.3 days, with typically 1.1" (28mm) of accumulated precipitation.

What is the snowiest month in Merrimack?

December is the month with the most snowfall in Merrimack. Snow falls for 4 days and accumulates 2.99" (76mm) of snow.

How much does it snow in Merrimack in December?

In Merrimack, New Hampshire, in December, during 4 snowfall days, 2.99" (76mm) of snow is typically accumulated.

What is the month with the shortest days in Merrimack?

December has the shortest days of the year, with an average of 9h and 6min of daylight.

How many hours of daylight does Merrimack have in December?

In December, the average day length is 9h and 5min.

When is the sunrise / sunset in December in Merrimack?

In December, on the first day of the month, sunrise is at 6:57 am and sunset at 4:12 pm. On the last day of the month, in Merrimack, sunrise is at 7:16 am and sunset at 4:21 pm EST.

How many hours of sunshine does Merrimack have in December?

In Merrimack, the average sunshine duration in December is 4.8h.

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

The months with the lowest UV index in Merrimack, New Hampshire, are January through March, November and December, with an average maximum UV index of 2.

What is the UV index reading in December in Merrimack?

The average daily maximum UV index in December is 2. A UV Index reading of 2, and below, represents a low health risk from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Merrimack, NH

Average temperature in December - Merrimack, NH
  • Average high temperature in December: 36.3°F

The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (30.6°F).

  • Average low temperature in December: 25.3°F

The month with the highest average low temperature is July (61°F).
The coldest month (with the lowest average low temperature) is January (18°F).

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Average pressure in December
Merrimack, NH

Average pressure in December - Merrimack, NH
  • Average pressure in December: 30.03"Hg

The month with the highest atmospheric pressure is November (30.07"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

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Average wind speed in December
Merrimack, NH

Average wind speed in December - Merrimack, NH
  • Average wind speed in December: 7.8mph

The windiest month (with the highest average wind speed) is January (8.3mph).
The calmest month (with the lowest average wind speed) is August (5.1mph).

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Average humidity in December
Merrimack, NH

Average humidity in December - Merrimack, NH
  • Average humidity in December: 79%

The month with the highest relative humidity is February (81%).
The month with the lowest relative humidity is April (72%).

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Average rainfall in December
Merrimack, NH

Average rainfall in December - Merrimack, NH
  • Average rainfall in December: 1.1"

The wettest month (with the highest rainfall) is October (1.38").
The driest month (with the least rainfall) is January (0.75").

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Average rainfall days in December
Merrimack, NH

Average rainfall days in December - Merrimack, NH
  • Average rainfall days in December: 6.3 days

The month with the highest number of rainy days is June (12.1 days).
The month with the least rainy days is January (4.1 days).

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Average snowfall in December
Merrimack, NH

Average snowfall in December - Merrimack, NH
  • Average snowfall in December: 2.99"

The month with the highest snowfall is December (2.99").
The months with the least snowfall are June, July, August and September (0").

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Average snowfall days in December
Merrimack, NH

Average snowfall days in December - Merrimack, NH
  • Average snowfall days in December: 4 days

The month with the highest number of snowfall days is January (7.1 days).
The months with the least snowfall days are June, July, August and September (0 days).

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Average daylight in December /
Average sunshine in December
Merrimack, NH

Average daylight in December / Average sunshine in December - Merrimack, NH
  • Average daylight in December: 9h and 1min

The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).

  • Average sunshine in December: 4h and 5min

The month with the most sunshine is August (Average sunshine: 10h and 24min).
The month with the least sunshine is February (Average sunshine: 4h and 36min).

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Average sunshine days in December
Merrimack, NH

Average sunshine days in December - Merrimack, NH
  • Average sunshine days in December: 21.3 days

The months with the most sunshine days are January and December (21.3 days).
The month with the least sunshine days is June (16.7 days).

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Average UV index in December
Merrimack, NH

Average UV index in December - Merrimack, NH
  • Average UV index in December: 2

The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 2).

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Average cloud cover in December
Merrimack, NH

Average cloud cover in December - Merrimack, NH
  • Average cloud cover in December: 47

The month with the most cloud cover is March (Cloud cover 51).
The month with the least cloud cover is August (Cloud cover 33).

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Average visibility in December
Merrimack, NH

Average visibility in December - Merrimack, NH
  • Average visibility in December: 6mi

The months with the highest visibility are January, April, November and December (6mi).
The months with the lowest visibility are February, March, May, June, July, August, September and October (5mi).

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Merrimack, New Hampshire, USA

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