Mystic
Connecticut, USA
Long-term weather forecast
Long-term weather forecast

December weather forecast and climate
Mystic, CT

December, the first month of the winter, in Mystic, is still a cold month, with average temperature fluctuating between 24.8°F (-4°C) and 41°F (5°C).

Temperature

In December, the average high-temperature decreases, from a cool 51.8°F (11°C) in November, to a cold 41°F (5°C). The average low-temperature, is 24.8°F (-4°C).

Rainfall

In Mystic, during December, the rain falls for 12 days and regularly aggregates up to 4.6" (116mm) of precipitation. Throughout the year, in Mystic, Connecticut, there are 122 rainfall days, and 48.1" (1222mm) of precipitation is accumulated.

Ocean temperature

In Mystic, Connecticut, the average water temperature is 48.6°F (9.2°C). Swimming in 48.6°F (9.2°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.

Daylight

The month with the shortest days is December, with an average of 9.2h of daylight.

Sunshine

Months with the least sunshine in Mystic, Connecticut, are November and December, with an average of 5h of sunshine.

UV index

With an average maximum UV index of 1, December is the month with the lowest UV index in Mystic. A UV Index estimate of 2, and below, represents a minimal health vulnerability from unsafe exposure to the UV radiation for the average person.
In December, the average maximum UV index of 1 translate into the following recommendations:
People with sensitive skin, children, and babies should always be protected from prolonged sun exposure. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.

What is the temperature in December in Mystic?

In December, in Mystic, the average high-temperature is 41°F (5°C), and the average low-temperature is 24.8°F (-4°C).

How much does it rain in Mystic in December?

In Mystic, Connecticut, in December, during 12 rainfall days, 4.6" (116mm) of precipitation is typically accumulated.

How cold is the water in December in Mystic?

In Mystic, in December, the average water temperature is 48.6°F (9.2°C). At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.

What is the month with the shortest days in Mystic?

With an average of 9.2h of daylight, December has the shortest days of the year in Mystic.

How many hours of daylight does Mystic have in December?

The average length of the day in December in Mystic is 9.2h.

What is the month with the least sunshine in Mystic?

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

How many hours of sunshine does Mystic have in December?

The average sunshine in December in Mystic is 5h.

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

December is the month with the lowest UV index in Mystic, Connecticut, with an average maximum UV index of 1.

What is the UV index reading in December in Mystic?

The average daily maximum UV index in December is 1. A UV Index value of 2, and less, symbolizes a low health threat from unsafe exposure to the Sun's UV rays.
Average temperature in December - Mystic, CT
  • Average high temperature in December: 41°F

The warmest month (with the highest average high temperature) is July (81°F).
The month with the lowest average high temperature is January (36°F).

  • Average low temperature in December: 25°F

The month with the highest average low temperature is July (63°F).
The coldest month (with the lowest average low temperature) is January (19°F).

Average rainfall in December - Mystic, CT
  • Average rainfall in December: 4.6"

The wettest month (with the highest rainfall) is November (4.8").
The driest month (with the lowest rainfall) is June (3.3").

Average rainfall days in December - Mystic, CT
  • Average rainfall days in December: 12 days

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

Average sea temperature in December - Mystic, CT
  • Average sea temperature in December: 48.6°F

The best month for swimming (with the highest average sea temperature) is August (70.3°F).
The coldest month (with the lowest average sea temperature) is February (37.9°F).

Average daylight in December / Average sunshine in December - Mystic, CT
  • Average daylight in December: 9.2h

The month with the longest days is June (Average daylight: 15.1h).
The month with shortest days is December (Average daylight: 9.2h).

  • Average sunshine in December: 5h

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

Average UV index in December - Mystic, CT
  • Average UV index in December: 1

Months with the highest UV index are June, July and August (UV index 8).
The month with the lowest UV index is December (UV index 1).