December weather forecast
St. Louis, MO

December in St. Louis is firmly within the winter season. Bitter cold conditions greet residents, often accompanied by snow. Temperatures plummet to their second-lowest of the year, averaging at 26.9°F (-2.8°C). As a result, the city experiences winter's first significant snowfall since the onset of the year-end season. The festive period culminates with city-wide Christmas and New Year celebrations, all under the spell of the winter magic.

Temperature

In December, the meteorological conditions in St. Louis alter, with the average high-temperature shifting from a mild 55.6°F (13.1°C) in November to a cold 42.4°F (5.8°C). In St. Louis, the average temperature during the nights of December drops to a freezing cold 27°F (-2.8°C).

Humidity

The most humid month in St. Louis is December, with an average relative humidity of 75.8%.

Rainfall

In December, in St. Louis, the rain falls for 9.4 days. Throughout December, 2.83" (72mm) of precipitation is accumulated. In St. Louis, during the entire year, the rain falls for 112.6 days and collects up to 40.94" (1040mm) of precipitation.

Snowfall

January through April, November and December are months with snowfall in St. Louis. In December, in St. Louis, it is snowing for 3.7 days. Throughout December, 4.41" (112mm) of snow is accumulated. Throughout the year, in St. Louis, there are 14.5 snowfall days, and 17.72" (450mm) of snow is accumulated.

Daylight

With an average of 9h and 30min of daylight, December has the shortest days of the year in St. Louis.
On the first day of the month, sunrise is at 7:00 am and sunset at 4:39 pm. On the last day of December, in St. Louis, sunrise is at 7:18 am and sunset at 4:49 pm CST.

Sunshine

With an average of 4.2h of sunshine, December has the least sunshine of the year in St. Louis.

UV index

The months with the lowest UV index in St. Louis are January and December, with an average maximum UV index of 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability from unsafe exposure to UV radiation for the ordinary person.
Note: The maximum daily UV index of 2 in December converts into the following recommendations:
Extended exposure to the sun should always be avoided by children, infants, and those with sensitive skin. The midday Sun can be dangerous due to its intense radiation; always find shade and reduce exposure. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation. Take heed! The reflection of snow can intensify the Sun's UV radiation nearly double.