December weather forecastIndex, WA
December
Weather in December
December, the first month of the winter in Index, is still a cold month, with temperature in the range of an average high of 38.3°F (3.5°C) and an average low of 28.6°F (-1.9°C).Temperature
December, with its average high-temperature of 38.3°F (3.5°C) and an average low-temperature of 28.6°F (-1.9°C), holds the record as the coldest month.Humidity
In Index, the average relative humidity in December is 87%.Rainfall
In Index, in December, it is raining for 19.9 days, with typically 7.48" (190mm) of accumulated precipitation. Throughout the year, there are 200.6 rainfall days, and 51.65" (1312mm) of precipitation is accumulated.Snowfall
Months with snowfall in Index are January through April, November and December. In Index, in December, during 3 snowfall days, 1.65" (42mm) of snow is typically accumulated. Throughout the year, in Index, there are 15.9 snowfall days, and 14.41" (366mm) of snow is accumulated.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 7:35 am and sunset at 4:15 pm. On the last day of December, in Index, sunrise is at 7:55 am and sunset at 4:24 pm PST.
Sunshine
January and December, with an average of 3.7h of sunshine, are months with the least sunshine.UV index
January through April, October through December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index estimate of 2, and below, represents a low health risk from unprotected exposure to Sun's UV rays for the ordinary person.Note: In December, a daily maximum UV index of 2 leads to the following instructions:
People with sensitive skin, children, and babies should always be protected from prolonged sun exposure. To avoid the Sun's strongest rays, limit exposure around the mid-day period. For excellent sun protection for the eyes, ears, face, and neck, consider a wide-brim hat. Be on the lookout! Nearly twofold UV radiation from the Sun can be reflected by snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Index, WA
- Average high temperature in December: 38.3°F
The warmest month (with the highest average high temperature) is August (73.4°F).
The month with the lowest average high temperature is December (38.3°F).
- Average low temperature in December: 28.6°F
The month with the highest average low temperature is August (48°F).
The coldest month (with the lowest average low temperature) is December (28.6°F).
Average pressure in December
Index, WA
- Average pressure in December: 30.09"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is August (29.99"Hg).
Average wind speed in December
Index, WA
- Average wind speed in December: 4.4mph
The windiest month (with the highest average wind speed) is January (4.8mph).
The calmest month (with the lowest average wind speed) is August (3.2mph).
Average humidity in December
Index, WA
- Average humidity in December: 87%
The months with the highest relative humidity are January, February and March (88%).
The month with the lowest relative humidity is July (72%).
Average rainfall in December
Index, WA
- Average rainfall in December: 7.48"
The wettest month (with the highest rainfall) is January (7.8").
The driest month (with the least rainfall) is August (0.79").
Average rainfall days in December
Index, WA
- Average rainfall days in December: 19.9 days
The month with the highest number of rainy days is March (22.3 days).
The month with the least rainy days is August (7.9 days).
Average snowfall in December
Index, WA
- Average snowfall in December: 1.65"
The month with the highest snowfall is February (5.43").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Index, WA
- Average snowfall days in December: 3 days
The month with the highest number of snowfall days is February (5.2 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
Index, WA
- Average daylight in December: 8h and 30min
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 and 42min
The month with the most sunshine is August (Average sunshine: 10h and 24min).
The months with the least sunshine are January and December (Average sunshine: 3h and 42min).
Average sunshine days in December
Index, WA
- Average sunshine days in December: 9.4 days
The month with the most sunshine days is August (19.9 days).
The month with the least sunshine days is March (7 days).
Average UV index in December
Index, WA
- Average UV index in December: 2
The month with the highest UV index is July (UV index 5).
The months with the lowest UV index are January, February, March, April, October, November and December (UV index 2).
Average cloud cover in December
Index, WA
- Average cloud cover in December: 61
The months with the most cloud cover are March and December (Cloud cover 61).
The month with the least cloud cover is August (Cloud cover 30).
Average visibility in December
Index, WA
- Average visibility in December: 4mi
The months with the highest visibility are May, June, July, August, September and October (5mi).
The months with the lowest visibility are January, February, March, April, November and December (4mi).
