December weather forecast and climate
St. Louis, MO

A beautiful twilight view of the Gateway Arch in St. Louis, Missouri, with a distant view of the city buildings mirrored in the waterfront
A beautiful twilight view of the Gateway Arch in St. Louis, Missouri, with a distant view of the city buildings mirrored in the waterfront
December, the first month of the winter, in St. Louis, is also a wintry month, with average temperature varying between 42.4°F (5.8°C) and 27°F (-2.8°C).

Temperature

In December, the average high-temperature in St. Louis decreases, from a mild 55.6°F (13.1°C) in November, to a wintry 42.4°F (5.8°C). The average low-temperature, in December, in St. Louis, is 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 St. Louis, during 9.4 rainfall days, 2.84" (72.1mm) of precipitation is typically accumulated. In St. Louis, during the entire year, the rain falls for 112.6 days and collects up to 40.96" (1040.3mm) of precipitation.

Snowfall

January through April, November and December are months with snowfall in St. Louis. In St. Louis, Missouri, snow falls for 3.7 days, with typically accumulated 4.4" (111.8mm) of snow. Throughout the year, in St. Louis, there are 14.5 snowfall days, and 17.7" (449.6mm) of snow is accumulated.

Daylight

The month with the shortest days in St. Louis, Missouri, is December, with an average of 9.5h of daylight.

Sunshine

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

UV index

January and December, with an average maximum UV index of 2, are months with the lowest UV index in St. Louis. A UV Index value of 2, and less, symbolizes a low threat to health from the exposure to the Sun's UV rays for the ordinary person.
Note: The daily maximum UV index of 2 interpret into the following advice:
Most people can stay in the Sun for up to 1 hour without burning, apart from children that always must be protected from sun exposure. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.

What is the temperature in December in St. Louis?

In St. Louis, in December, the average high-temperature is 42.4°F (5.8°C), and the average low-temperature is 27°F (-2.8°C).

What is the most humid month in St. Louis?

With an average relative humidity of 75.8%, December is the most humid month.

What is the average humidity in December in St. Louis?

In St. Louis, Missouri, the average relative humidity in December is 75.8%.

How much does it rain in St. Louis in December?

In St. Louis, in December, it is raining for 9.4 days, with typically 2.84" (72.1mm) of accumulated precipitation.

How many days does it snow in December in St. Louis?

In St. Louis, during December, snow falls for 3.7 days and regularly aggregates up to 4.4" (111.8mm) of snow.

What is the month with the shortest days in St. Louis?

December has the shortest days of the year in St. Louis, Missouri, with an average of 9.5h of daylight.

What is the average length of the day in December in St. Louis?

In December, the average length of the day in St. Louis, Missouri, is 9.5h.

What is the month with the least sunshine in St. Louis?

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

How many hours of sunshine does St. Louis have in December?

In December, the average sunshine in St. Louis, Missouri, is 4.2h.

When is the lowest UV index in St. Louis?

Months with the lowest UV index in St. Louis are January and December, with an average maximum UV index of 2.

How high is the UV index in December in St. Louis?

The average daily maximum UV index in December in St. Louis is 2. A UV Index reading of 2, and below, represents a low health risk from unprotected exposure to the UV radiation.
Average temperature in December - St. Louis, MO
  • Average high temperature in December: 5.8°C

The warmest month (with the highest average high temperature) is July (31.7°C).
The month with the lowest average high temperature is January (4.4°C).

  • Average low temperature in December: -2.8°C

The month with the highest average low temperature is July (21.7°C).
The coldest month (with the lowest average low temperature) is January (-4.6°C).

Average humidity in December - St. Louis, MO
  • Average humidity in December: 75.8%

The month with the highest relative humidity is December (75.8%).
The month with the lowest relative humidity is April (63.5%).

Average rainfall in December - St. Louis, MO
  • Average rainfall in December: 72.1mm

The wettest month (with the highest rainfall) is May (119.9mm).
The driest month (with the least rainfall) is February (56.9mm).

Average rainfall days in December - St. Louis, MO
  • Average rainfall days in December: 9.4 days

The month with the highest number of rainy days is May (11.9 days).
The month with the least rainy days is September (7.4 days).

Average snowfall in December - St. Louis, MO
  • Average snowfall in December: 111.8mm

The month with the highest snowfall is January (142.2mm).
Months with the least snowfall are May, June, July, August, September and October (0mm).

Average snowfall days in December - St. Louis, MO
  • Average snowfall days in December: 3.7 days

The month with the highest number of snowfall days is January (4.7 days).
Months with the least snowfall days are May, June, July, August, September and October (0 days).

Average daylight in December / Average sunshine in December - St. Louis, MO
  • Average daylight in December: 9.5h

The month with the longest days is June (Average daylight: 14.8h).
The month with the shortest days is December (Average daylight: 9.5h).

  • Average sunshine in December: 4.2h

The month with the most sunshine is July (Average sunshine: 10h).
The month with the least sunshine is December (Average sunshine: 4.2h).

Average UV index in December - St. Louis, MO
  • Average UV index in December: 2

Months with the highest UV index are June, July and August (UV index 9).
Months with the lowest UV index are January and December (UV index 2).