December weather forecast
Grand Isle, LA

The scenic Grand Isle, Louisiana, with a view of the numerous houses and the extended piers onto the calm seawater
The scenic Grand Isle, Louisiana, with a view of the numerous houses and the extended piers onto the calm seawater

Weather in December

December, the first month of the winter in Grand Isle, is still a comfortable month, with an average temperature fluctuating between 64.9°F (18.3°C) and 56.7°F (13.7°C).

Temperature

In Grand Isle, the average high-temperature in December is essentially the same as in November - a comfortable 64.9°F (18.3°C). In December, the average low-temperature is 56.7°F (13.7°C).

Humidity

The months with the highest humidity in Grand Isle are February and December, with an average relative humidity of 78%.

Rainfall

In December, in Grand Isle, Louisiana, the rain falls for 11.9 days. Throughout December, 1.65" (42mm) of precipitation is accumulated. In Grand Isle, during the entire year, the rain falls for 151.9 days and collects up to 22.01" (559mm) of precipitation.

Snowfall

February through December are months without snowfall in Grand Isle.

Ocean temperature

In Grand Isle, the average water temperature is 64.2°F (17.9°C).
Note: Swimming in 64.2°F (17.9°C) is not enjoyable for the majority. Controlling breathing becomes progressively more difficult as surface water temperature decreases below 69.8°F (21°C).

Daylight

The month with the shortest days in Grand Isle is December, with an average of 10h and 19min of daylight.
On the first day of the month, sunrise is at 6:36 am and sunset at 5:01 pm. On the last day of December, sunrise is at 6:53 am and sunset at 5:12 pm CST.

Sunshine

The month with the least sunshine in Grand Isle is December, with an average of 5.4h of sunshine.

UV index

January and December, with an average maximum UV index of 4, are months with the lowest UV index in Grand Isle. A UV Index value of 3 to 5 symbolizes a medium health hazard from unsafe exposure to UV radiation for the average person.
Note: In December, the average maximum UV index of 4 translate into the following recommendations:
Take precautions - Protection against sun damage is advised. 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.
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FAQ

What is the temperature in December in Grand Isle?

The average high-temperature, in December, is 64.9°F (18.3°C), while the average low-temperature is 56.7°F (13.7°C). in September, the average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), which factors the actual air temperature with the relative humidity, is calculated to be 93.2°F (34°C).

What is the most humid month in Grand Isle?

February and December, with an average relative humidity of 78%, are most humid months in Grand Isle.

What is the average humidity in December in Grand Isle?

In Grand Isle, the average relative humidity in December is 78%.

How many days does it rain in December in Grand Isle?

In Grand Isle, Louisiana, during December, the rain falls for 11.9 days and regularly aggregates up to 1.65" (42mm) of precipitation.

When it does not snow in Grand Isle?

February through December are months without snowfall.

Does it snow in Grand Isle in December?

In Grand Isle, in December, it doesn't snow. In January, it regularly snows.

How cold is the water in December in Grand Isle?

In Grand Isle, Louisiana, the average seawater temperature in December is 64.2°F (17.9°C). For swimming, a surface water temperature of 64.2°F (17.9°C) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 69.8°F (21°C).

What is the month with the shortest days in Grand Isle?

The month with the shortest days is December, with an average of 10h and 19min of daylight.

How many hours of daylight does Grand Isle have in December?

In Grand Isle, Louisiana, the average day length in December is 10h and 19min.

What time are sunrise and sunset in December in Grand Isle?

In December, on the first day of the month, sunrise is at 6:36 am and sunset at 5:01 pm. On the last day of the month, sunrise is at 6:53 am and sunset at 5:12 pm CST.

What is the month with the least sunshine in Grand Isle?

The month with the least sunshine in Grand Isle, Louisiana, is December, with an average of 5.4h of sunshine.

How long on average sun shines in December in Grand Isle?

In December, the average sunshine duration is 5.4h.

What are the months with the lowest UV index in Grand Isle?

January and December, with an average maximum UV index of 4, are months with the lowest UV index.

What is the UV index reading in December in Grand Isle?

In December, the average daily maximum UV index is 4. A UV Index of 3 to 5 symbolizes a moderate vulnerability from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Grand Isle, LA

Average temperature in December - Grand Isle, LA
  • Average high temperature in December: 64.9°F

The warmest months (with the highest average high temperature) are July and August (86.9°F).
The month with the lowest average high temperature is January (61.7°F).

  • Average low temperature in December: 56.7°F

The month with the highest average low temperature is August (81.3°F).
The coldest month (with the lowest average low temperature) is January (53.1°F).

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Average pressure in December
Grand Isle, LA

Average pressure in December - Grand Isle, LA
  • Average pressure in December: 30.11"Hg

The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is September (29.96"Hg).

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Average wind speed in December
Grand Isle, LA

Average wind speed in December - Grand Isle, LA
  • Average wind speed in December: 12.2mph

The windiest month (with the highest average wind speed) is January (12.4mph).
The calmest month (with the lowest average wind speed) is July (8mph).

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Average humidity in December
Grand Isle, LA

Average humidity in December - Grand Isle, LA
  • Average humidity in December: 78%

The months with the highest relative humidity are February and December (78%).
The month with the lowest relative humidity is October (71%).

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Average rainfall in December
Grand Isle, LA

Average rainfall in December - Grand Isle, LA
  • Average rainfall in December: 1.65"

The wettest month (with the highest rainfall) is August (4.72").
The driest months (with the least rainfall) are February and April (0.87").

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Average rainfall days in December
Grand Isle, LA

Average rainfall days in December - Grand Isle, LA
  • Average rainfall days in December: 11.9 days

The month with the highest number of rainy days is August (20.7 days).
The month with the least rainy days is November (7.5 days).

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Average snowfall days in December
Grand Isle, LA

Average snowfall days in December - Grand Isle, LA
  • Average snowfall days in December: 0 days

The month with the highest number of snowfall days is January (0.1 days).
The months with the least snowfall days are February, March, April, May, June, July, August, September, October, November and December (0 days).

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Average sea temperature in December
Grand Isle, LA

Average sea temperature in December - Grand Isle, LA
  • Average sea temperature in December: 64.1°F

The best month for swimming (with the highest average sea temperature) is August (87.5°F).
The coldest month (with the lowest average sea temperature) is January (61.4°F).

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Average daylight in December /
Average sunshine in December
Grand Isle, LA

Average daylight in December / Average sunshine in December - Grand Isle, LA
  • Average daylight in December: 10h and 19min

The month with the longest days is June (Average daylight: 13h and 59min).
The month with the shortest days is December (Average daylight: 10h and 19min).

  • Average sunshine in December: 5h and 24min

The month with the most sunshine is June (Average sunshine: 11h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 24min).

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Average sunshine days in December
Grand Isle, LA

Average sunshine days in December - Grand Isle, LA
  • Average sunshine days in December: 16.3 days

The month with the most sunshine days is November (19.5 days).
The month with the least sunshine days is August (6.5 days).

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Average UV index in December
Grand Isle, LA

Average UV index in December - Grand Isle, LA
  • Average UV index in December: 4

The months with the highest UV index are May, June, July, August and September (UV index 7).
The months with the lowest UV index are January and December (UV index 4).

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Average cloud cover in December
Grand Isle, LA

Average cloud cover in December - Grand Isle, LA
  • Average cloud cover in December: 42

The month with the most cloud cover is December (Cloud cover 42).
The month with the least cloud cover is May (Cloud cover 23).

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Average visibility in December
Grand Isle, LA

Average visibility in December - Grand Isle, LA
  • Average visibility in December: 6mi

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

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