December weather forecast
Isle Royale National Park, MI

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Calm evening waters at the Rock Harbor in Isle Royale National Park, Michigan, USA
Calm evening waters at the Rock Harbor in Isle Royale National Park, Michigan, USA

Weather in December

December witnesses the onset of winter, concluding the cycle of the year. Cold weather characterizes this month, increasing from the cool temperatures of November. Daylight hours are curtailed dramatically, indicating the waning of the Sun. Expected rainfall remains relatively consistent compared to the previous month. The temperature typically fluctuates from 7°F (-13.9°C) to 23°F (-5°C), indicating the reinstatement of the chilling winter.

Temperature

The onset of December coincides with a reduction in the average high-temperature, falling from an icy 35.6°F (2°C) in November to a subzero cold 23°F (-5°C). In the month of December, Isle Royale National Park witnesses a consistent average low-temperature of 6.8°F (-14°C).

Rainfall

In December, in Isle Royale National Park, the rain falls for 11 days. Throughout December, 2.32" (59mm) of precipitation is accumulated. Throughout the year, in Isle Royale National Park, there are 125 rainfall days, and 30.55" (776mm) of precipitation is accumulated.

Ocean temperature

In Isle Royale National Park, in December, the average water temperature is 39.2°F (4°C).
Note: 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.

Daylight

The month with the shortest days is December, with an average of 8h and 30min of daylight.
On the first day of the month, sunrise is at 8:25 am and sunset at 5:04 pm. On the last day of December, in Isle Royale National Park, Michigan, sunrise is at 8:45 am and sunset at 5:12 pm EST.

Sunshine

November and December, with an average of 3h of sunshine, are months with the least sunshine.

UV index

The months with the lowest UV index in Isle Royale National Park, Michigan, are January, February, November and December, with an average maximum UV index of 1. A UV Index value of 2, and less, symbolizes a minimal health vulnerability from exposure to the Sun's UV rays for ordinary individuals.
Note: The maximum UV index of 1 during December leads to these instructions:
Although prolonged sun exposure does not typically bother most people, children, babies, and those with sensitive skin should always have protection. Protect yourself from the midday Sun's peak UV radiation by minimizing exposure. During bright days, sunglasses that offer UVA and UVB defense are recommended.

Frequently asked questions

How cold is it in Isle Royale National Park in December?

In Isle Royale National Park, 23°F (-5°C) is the average high-temperature and 6.8°F (-14°C) is the average low-temperature during December.

How many days does it rain in December in Isle Royale National Park?

In December, the rain falls for 11 days. Throughout December, 2.32" (59mm) of precipitation is accumulated.

How cold is the water in December in Isle Royale National Park?

In Isle Royale National Park, in December, the average water temperature is 39.2°F (4°C). For swimming, this is considered life-threatening and very dangerous. The water feels painfully cold, and hyperventilation quickly occurs. A specialized swimsuit is mandatory to reduce thermal damage.

What is the month with the shortest days in Isle Royale National Park?

The month with the shortest days is December, with an average of 8h and 30min of daylight.

How many hours of daylight does Isle Royale National Park have in December?

In December, the average day length in Isle Royale National Park, Michigan, is 8h and 27min.

When is the sunrise / sunset in December in Isle Royale National Park?

In December, on the first day of the month, sunrise is at 8:25 am and sunset at 5:04 pm. On the last day of the month, sunrise is at 8:45 am and sunset at 5:12 pm EST.

What is the month with the least sunshine in Isle Royale National Park?

November and December, with an average of 3h of sunshine, are months with the least sunshine in Isle Royale National Park, Michigan.

How many hours of sunshine does Isle Royale National Park have in December?

In Isle Royale National Park, the average sunshine duration in December is 3h.

What are the months with the lowest UV index in Isle Royale National Park?

The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 1.

How high is the UV index in December in Isle Royale National Park?

The average daily maximum UV index in December is 1. A UV Index estimate of 2, and below, represents a minimal hazard to health from exposure to Sun's UV rays.
Average high temperature
Average rainfall days
Average sea temperature
Average daylight
Average sunshine
Average UV index

Average temperature in December
Isle Royale National Park, MI

Average temperature in December - Isle Royale National Park, MI
  • Average high temperature in December: 23°F

The warmest month (with the highest average high temperature) is July (75°F).
The month with the lowest average high temperature is January (18°F).

  • Average low temperature in December: 7°F

The month with the highest average low temperature is July (54°F).
The coldest month (with the lowest average low temperature) is January (0°F).

Average rainfall in December
Isle Royale National Park, MI

Average rainfall in December - Isle Royale National Park, MI
  • Average rainfall in December: 2.3"

The wettest month (with the highest rainfall) is September (3.4").
The driest month (with the least rainfall) is February (1.5").

Average rainfall days in December
Isle Royale National Park, MI

Average rainfall days in December - Isle Royale National Park, MI
  • Average rainfall days in December: 11 days

The months with the highest number of rainy days are June and September (13 days).
The months with the least rainy days are February and April (8 days).

Average sea temperature in December
Isle Royale National Park, MI

Average sea temperature in December - Isle Royale National Park, MI
  • Average sea temperature in December: 39°F

The best month for swimming (with the highest average sea temperature) is August (55°F).
The coldest months (with the lowest average sea temperature) are January, February, March and April (36°F).

Average daylight in December /
Average sunshine in December
Isle Royale National Park, MI

Average daylight in December / Average sunshine in December - Isle Royale National Park, MI
  • Average daylight in December: 8h and 3min

The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 30min).

  • Average sunshine in December: 3h

The month with the most sunshine is July (Average sunshine: 10h).
The months with the least sunshine are November and December (Average sunshine: 3h).

Average UV index in December
Isle Royale National Park, MI

Average UV index in December - Isle Royale National Park, MI
  • Average UV index in December: 1

The months with the highest UV index are June and July (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 1).

Isle Royale National Park, Michigan, USA

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