December weather forecast
Byron, IL

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Weather in December

December, the first month of the winter in Byron, is also a wintry month, with an average temperature fluctuating between 32.5°F (0.3°C) and 22.5°F (-5.3°C).

Temperature

The commencement of December involves a temperature shift, with the average high-temperature dropping from a chilly 44.8°F (7.1°C) in November to a cold 32.5°F (0.3°C). Byron, in December, observes a steady average low-temperature of 22.5°F (-5.3°C).

Humidity

In Byron, the average relative humidity in December is 83%.

Rainfall

In Byron, in December, it is raining for 4.6 days, with typically 0.39" (10mm) of accumulated precipitation. Throughout the year, there are 100.6 rainfall days, and 7.99" (203mm) of precipitation is accumulated.

Snowfall

January through April, October through December are months with snowfall. In Byron, during December, snow falls for 6.6 days and regularly aggregates up to 0.35" (9mm) of snow. In Byron, during the entire year, snow falls for 29.5 days and aggregates up to 3.66" (93mm) of snow.

Daylight

The month with the shortest days is December, with an average of 9h and 12min of daylight.
On the first day of the month, sunrise is at 7:06 am and sunset at 4:26 pm. On the last day of December, sunrise is at 7:25 am and sunset at 4:35 pm CST.

Sunshine

In December, the average sunshine is 3.9h.

UV index

January and December, with an average maximum UV index of 1, are months with the lowest UV index. A UV Index of 2, and less, symbolizes a low threat to health from exposure to the Sun's UV rays for average individuals.
Note: In December, a regular UV index of 1 translates into these guidelines:
Babies, children, and those with sensitive skin should always avoid extended periods in the sun. The Sun is most powerful around mid-day, so it's a good practice to reduce direct exposure. Prioritize a wide-brim hat for comprehensive sun defense for your face, neck, eyes, and ears. Foresee this! The reflection from snow can nearly double the intensity of UV radiation from the Sun.
Updated: Jun 21, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold is December?

The high-temperature, in December, in Byron, records 32.5°F (0.3°C), while the low-temperature is 22.5°F (-5.3°C).

What is the average humidity in December?

In December, the average relative humidity is 83%.

How many days does it rain in December?

In December, the rain falls for 4.6 days. Throughout December, 0.39" (10mm) of precipitation is accumulated.

How many days does it snow in December?

In Byron, in December, during 6.6 snowfall days, 0.35" (9mm) of snow is typically accumulated.

What is the month with the shortest days?

December has the shortest days of the year, with an average of 9h and 12min of daylight.

What is the average length of the day in December?

In Byron, Illinois, the average day length in December is 9h and 10min.

What time are sunrise and sunset in December?

On the first day of December, sunrise is at 7:06 am and sunset at 4:26 pm. On the last day of the month, sunrise is at 7:25 am and sunset at 4:35 pm CST.

How many hours of sunshine does Byron have in December?

The average sunshine duration in December is 3.9h.

When is the lowest UV index?

January and December, with an average maximum UV index of 1, are months with the lowest UV index.

What is the UV index reading in December?

In December, the average daily maximum UV index in Byron is 1. A UV Index estimate of 2, and below, represents a low health risk from unsafe 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
Byron, IL

Average temperature in December - Byron, IL
  • Average high temperature in December: 32.5°F

The warmest month (with the highest average high temperature) is July (79.9°F).
The month with the lowest average high temperature is January (26.2°F).

  • Average low temperature in December: 22.5°F

The month with the highest average low temperature is July (63.1°F).
The coldest month (with the lowest average low temperature) is January (14°F).

Average pressure in December
Byron, IL

Average pressure in December - Byron, IL
  • Average pressure in December: 30.1"Hg

The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

Average wind speed in December
Byron, IL

Average wind speed in December - Byron, IL
  • Average wind speed in December: 9.4mph

The windiest month (with the highest average wind speed) is April (10.2mph).
The calmest month (with the lowest average wind speed) is August (6.3mph).

Average humidity in December
Byron, IL

Average humidity in December - Byron, IL
  • Average humidity in December: 83%

The month with the highest relative humidity is January (86%).
The months with the lowest relative humidity are April and October (75%).

Average rainfall in December
Byron, IL

Average rainfall in December - Byron, IL
  • Average rainfall in December: 0.39"

The wettest month (with the highest rainfall) is May (1.18").
The driest months (with the least rainfall) are January and February (0.35").

Average rainfall days in December
Byron, IL

Average rainfall days in December - Byron, IL
  • Average rainfall days in December: 4.6 days

The month with the highest number of rainy days is May (13.8 days).
The month with the least rainy days is January (3.2 days).

Average snowfall in December
Byron, IL

Average snowfall in December - Byron, IL
  • Average snowfall in December: 0.35"

The month with the highest snowfall is January (1.42").
The months with the least snowfall are May, June, July, August and September (0").

Average snowfall days in December
Byron, IL

Average snowfall days in December - Byron, IL
  • Average snowfall days in December: 6.6 days

The month with the highest number of snowfall days is January (8.1 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

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

Average daylight in December / Average sunshine in December - Byron, IL
  • Average daylight in December: 9h and 1min

The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).

  • Average sunshine in December: 3h and 5min

The month with the most sunshine is July (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).

Average sunshine days in December
Byron, IL

Average sunshine days in December - Byron, IL
  • Average sunshine days in December: 22.6 days

The month with the most sunshine days is December (22.6 days).
The month with the least sunshine days is June (12.8 days).

Average UV index in December
Byron, IL

Average UV index in December - Byron, IL
  • Average UV index in December: 1

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).

Average cloud cover in December
Byron, IL

Average cloud cover in December - Byron, IL
  • Average cloud cover in December: 59

The month with the most cloud cover is January (Cloud cover 62).
The month with the least cloud cover is September (Cloud cover 33).

Average visibility in December
Byron, IL

Average visibility in December - Byron, IL
  • Average visibility in December: 6mi

The months with the highest visibility are February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are January, July and August (5mi).

Byron, Illinois, USA

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