December weather forecast
Waterloo, IL

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Weather in December

The first month of the winter, December, is also a frosty month in Waterloo, Illinois, with an average temperature varying between 43.2°F (6.2°C) and 30.9°F (-0.6°C).

Temperature

In Waterloo, the beginning of December is marked by a lowered average high-temperature, shifting from November's cool 53.6°F (12°C) to a chilly 43.2°F (6.2°C). Throughout December nights, Waterloo experiences a consistent temperature average of 30.9°F (-0.6°C).

Humidity

In December, the average relative humidity is 76%.

Rainfall

In Waterloo, during December, the rain falls for 8.1 days and regularly aggregates up to 1.77" (45mm) of precipitation. Throughout the year, there are 139.8 rainfall days, and 25.63" (651mm) of precipitation is accumulated.

Snowfall

January through March, September, November and December are months with snowfall in Waterloo, Illinois. In Waterloo, in December, snow falls for 3.5 days, with typically accumulated 1.54" (39mm) of snow. Throughout the year, there are 18.7 snowfall days, and 6.65" (169mm) of snow is accumulated.

Daylight

The month with the shortest days is December, with an average of 9h and 30min of daylight.
On the first day of December, sunrise is at 6:59 am and sunset at 4:40 pm. On the last day of the month, sunrise is at 7:17 am and sunset at 4:50 pm CST.

Sunshine

In Waterloo, the average sunshine in December is 5h.

UV index

The months with the lowest UV index are January, February and December, with an average maximum UV index of 2. A UV Index of 2, and less, symbolizes a minimal health hazard from unsafe exposure to UV radiation for average individuals.
Note: The UV index of 2 during December translates into the following guidance:
Children, infants, and individuals with sensitive skin should be constantly protected from extended sun exposure. Midday is when the Sun's radiation is strongest; avoid prolonged exposure during this time. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense. Notice! The UV radiation of the Sun can be intensified nearly twofold due to the reflective quality of snow.
Updated: Feb 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

Is December cold in Waterloo?

In December, the average high-temperature and low-temperature in Waterloo, Illinois, are 43.2°F (6.2°C) and 30.9°F (-0.6°C) respectively. In August, the average heat index (a.k.a. 'feels like', 'apparent temperature'), which represents the influence of relative humidity on air temperature, is computed to be 95°F (35°C).

What is the average humidity in December in Waterloo?

In December, the average relative humidity is 76%.

How many days does it rain in December in Waterloo?

In December, the rain falls for 8.1 days. Throughout December, 1.77" (45mm) of precipitation is accumulated.

How many days does it snow in December in Waterloo?

In Waterloo, Illinois, in December, during 3.5 snowfall days, 1.54" (39mm) of snow is typically accumulated.

What is the month with the shortest days in Waterloo?

With an average of 9h and 30min of daylight, December has the shortest days of the year in Waterloo, Illinois.

What is the average length of the day in December in Waterloo?

In Waterloo, Illinois, the average day length in December is 9h and 33min.

When is the sunrise / sunset in December in Waterloo?

On the first day of December in Waterloo, Illinois, sunrise is at 6:59 am and sunset at 4:40 pm. On the last day of the month, sunrise is at 7:17 am and sunset at 4:50 pm CST.

How long on average sun shines in December in Waterloo?

The average sunshine duration in December in Waterloo is 5h.

When is the lowest UV index in Waterloo?

The months with the lowest UV index in Waterloo are January, February and December, with an average maximum UV index of 2.

What is the UV index reading in December in Waterloo?

The average daily maximum UV index in December in Waterloo is 2. A UV Index of 2, and less, symbolizes a low health threat from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Waterloo, IL

Average temperature in December - Waterloo, IL
  • Average high temperature in December: 43.2°F

The warmest month (with the highest average high temperature) is July (87.3°F).
The month with the lowest average high temperature is January (38.3°F).

  • Average low temperature in December: 30.9°F

The month with the highest average low temperature is July (68.7°F).
The coldest month (with the lowest average low temperature) is January (25.2°F).

Average pressure in December
Waterloo, IL

Average pressure in December - Waterloo, IL
  • Average pressure in December: 30.13"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

Average wind speed in December
Waterloo, IL

Average wind speed in December - Waterloo, IL
  • Average wind speed in December: 8.5mph

The windiest month (with the highest average wind speed) is January (9.3mph).
The calmest months (with the lowest average wind speed) are July and August (5.5mph).

Average humidity in December
Waterloo, IL

Average humidity in December - Waterloo, IL
  • Average humidity in December: 76%

The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (71%).

Average rainfall in December
Waterloo, IL

Average rainfall in December - Waterloo, IL
  • Average rainfall in December: 1.77"

The wettest month (with the highest rainfall) is May (3.19").
The driest months (with the least rainfall) are February and November (1.34").

Average rainfall days in December
Waterloo, IL

Average rainfall days in December - Waterloo, IL
  • Average rainfall days in December: 8.1 days

The month with the highest number of rainy days is July (16.2 days).
The month with the least rainy days is January (6.3 days).

Average snowfall in December
Waterloo, IL

Average snowfall in December - Waterloo, IL
  • Average snowfall in December: 1.54"

The month with the highest snowfall is January (1.89").
The months with the least snowfall are April, May, June, July, August and October (0").

Average snowfall days in December
Waterloo, IL

Average snowfall days in December - Waterloo, IL
  • Average snowfall days in December: 3.5 days

The month with the highest number of snowfall days is January (6.3 days).
The months with the least snowfall days are May, June, July, August and October (0 days).

Average daylight in December /
Average sunshine in December
Waterloo, IL

Average daylight in December / Average sunshine in December - Waterloo, IL
  • Average daylight in December: 9h and 3min

The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).

  • Average sunshine in December: 5h and 0min

The months with the most sunshine are June and July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 42min).

Average sunshine days in December
Waterloo, IL

Average sunshine days in December - Waterloo, IL
  • Average sunshine days in December: 20.4 days

The month with the most sunshine days is January (20.6 days).
The month with the least sunshine days is July (12.5 days).

Average UV index in December
Waterloo, IL

Average UV index in December - Waterloo, IL
  • Average UV index in December: 2

The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February and December (UV index 2).

Average cloud cover in December
Waterloo, IL

Average cloud cover in December - Waterloo, IL
  • Average cloud cover in December: 47

The month with the most cloud cover is January (Cloud cover 49).
The months with the least cloud cover are June and August (Cloud cover 27).

Average visibility in December
Waterloo, IL

Average visibility in December - Waterloo, IL
  • 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).

Waterloo, Illinois, USA

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