Contents
- Weather in December
- Frequently asked questions
- Average temperature in December
- Average pressure in December
- Average wind speed in December
- Average humidity in December
- Average rainfall in December
- Average rainfall days in December
- Average snowfall in December
- Average snowfall days in December
- Average daylight in December
- Average sunshine in December
- Average sunshine days in December
- Average UV index in December
- Average cloud cover in December
- Average visibility in December
Weather in December
Temperature
December is the month when Saint Helens experiences its coldest temperatures, averaging a high of 41.9°F (5.5°C) and a low of 31.8°F (-0.1°C).Humidity
The average relative humidity in December is 87%.Rainfall
In Saint Helens, during December, the rain falls for 15 days and regularly aggregates up to 2.52" (64mm) of precipitation. Throughout the year, there are 149 rainfall days, and 19.37" (492mm) of precipitation is accumulated.Snowfall
January through April, November and December are months with snowfall. In December, it is snowing for 1.2 days. Throughout December, 0.43" (11mm) of snow is accumulated. Throughout the year, in Saint Helens, there are 10.2 snowfall days, and 5.91" (150mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 8h and 42min of daylight.On the first day of the month, sunrise is at 7:33 am and sunset at 4:28 pm. On the last day of December, sunrise is at 7:52 am and sunset at 4:36 pm PST.
Sunshine
January, February and December, with an average of 3.7h of sunshine, are months with the least sunshine.UV index
In Saint Helens, Oregon, the average daily maximum UV index in December is 2. A UV Index value of 2, and less, symbolizes a low threat to health from unprotected exposure to Sun's UV rays for ordinary individuals.Note: In December, the maximum UV index of 2 suggests these recommendations:
Prolonged sun exposure should always be prevented in babies, children, and those with sensitive skin. The intensity of the Sun's UV radiation during midday suggests reducing time spent outdoors. Tightly woven clothing, when worn loosely, shields effectively against the Sun. Alert! The snow's reflection can amplify the UV radiation of the Sun nearly twice.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What part of the year is the coldest?
Is it cold during December?
What is the average humidity in December?
How much does it rain in December?
How many days does it snow in December in Saint Helens?
What is the month with the shortest days?
How many hours of daylight does Saint Helens have in December?
What time are sunrise and sunset in December?
What is the month with the least sunshine?
How long on average sun shines in December in Saint Helens?
How high is the UV index in December?
Average temperature in December
Saint Helens, OR
- Average high temperature in December: 41.9°F
The warmest month (with the highest average high temperature) is August (76.5°F).
The month with the lowest average high temperature is December (41.9°F).
- Average low temperature in December: 31.8°F
The month with the highest average low temperature is August (47.8°F).
The coldest month (with the lowest average low temperature) is December (31.8°F).
Average pressure in December
Saint Helens, OR
- Average pressure in December: 30.09"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The months with the lowest atmospheric pressure are August and September (30.01"Hg).
Average wind speed in December
Saint Helens, OR
- Average wind speed in December: 4.9mph
The windiest month (with the highest average wind speed) is January (5.3mph).
The calmest month (with the lowest average wind speed) is August (3.5mph).
Average humidity in December
Saint Helens, OR
- Average humidity in December: 87%
The month with the highest relative humidity is February (88%).
The months with the lowest relative humidity are July and August (72%).
Average rainfall in December
Saint Helens, OR
- Average rainfall in December: 2.52"
The wettest month (with the highest rainfall) is January (2.64").
The driest month (with the least rainfall) is July (0.31").
Average rainfall days in December
Saint Helens, OR
- Average rainfall days in December: 15 days
The month with the highest number of rainy days is March (16 days).
The month with the least rainy days is July (5.9 days).
Average snowfall in December
Saint Helens, OR
- Average snowfall in December: 0.43"
The month with the highest snowfall is January (1.97").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Saint Helens, OR
- Average snowfall days in December: 1.2 days
The month with the highest number of snowfall days is February (3.6 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
Saint Helens, OR
- Average daylight in December: 8h and 4min
The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).
- Average sunshine in December: 3h and 4min
The month with the most sunshine is August (Average sunshine: 10h and 24min).
The months with the least sunshine are January, February and December (Average sunshine: 3h and 42min).
Average sunshine days in December
Saint Helens, OR
- Average sunshine days in December: 13.9 days
The month with the most sunshine days is July (23.7 days).
The month with the least sunshine days is February (12.1 days).
Average UV index in December
Saint Helens, OR
- Average UV index in December: 2
The month with the highest UV index is July (UV index 5).
The month with the lowest UV index is November (UV index 1).
Average cloud cover in December
Saint Helens, OR
- Average cloud cover in December: 61
The month with the most cloud cover is March (Cloud cover 63).
The month with the least cloud cover is August (Cloud cover 32).
Average visibility in December
Saint Helens, OR
- Average visibility in December: 4mi
The months with the highest visibility are July and August (5mi).
The months with the lowest visibility are January, February, March, April, May, June, September, October, November and December (4mi).
Saint Helens, Oregon, USA
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