January weather forecast and climate
Decatur, IL

Weather in January

January, like December, in Decatur, Illinois, is another cold winter month, with average temperature varying between 21.2°F (-6°C) and 32.9°F (0.5°C).

Temperature

The coldest month is January, with an average high-temperature of 32.9°F (0.5°C) and an average low-temperature of 21.2°F (-6°C).

Humidity

In Decatur, the average relative humidity in January is 79%.

Rainfall

In Decatur, Illinois,, it is raining for 6.3 days, with typically 1.06" (27mm) of accumulated precipitation. Throughout the year, there are 130.2 rainfall days, and 16.34" (415mm) of precipitation is accumulated.

Snowfall

January through April, November and December are months with snowfall. January is the month with the most snowfall in Decatur. Snow falls for 7.2 days and accumulates 1.85" (47mm) of snow.

Daylight

In January, the average length of the day is 9.7h.

Sunshine

January has the least sunshine of the year, with an average of 4.1h of sunshine.

UV index

January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Decatur. A UV Index reading of 2, and below, represents a low threat to health from the exposure to the Sun's UV radiation for average individuals.
Note: In January, the average maximum UV index of 2 translate into the following recommendations:
For the majority, extended sun exposure is not of great concern. Infants and people with sensitive skin must always be protected. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
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FAQ

What is the coldest month in Decatur?

The coldest month in Decatur is January, with an average high-temperature of 32.9°F (0.5°C) and an average low-temperature of 21.2°F (-6°C).

What is the average humidity in January in Decatur?

The average relative humidity in January is 79%.

How many days does it rain in January in Decatur?

In Decatur, Illinois, in January, it is raining for 6.3 days, with typically 1.06" (27mm) of accumulated precipitation.

What is the snowiest month in Decatur?

The month with the most snowfall is January when snow falls for 7.2 days and typically aggregates up to 1.85" (47mm) of snow.

How much does it snow in Decatur in January?

In Decatur, during January, snow falls for 7.2 days and regularly aggregates up to 1.85" (47mm) of snow.

How many hours of daylight does Decatur have in January?

In January, the average length of the day is 9.7h.

What is the month with the least sunshine in Decatur?

With an average of 4.1h of sunshine, January has the least sunshine of the year in Decatur, Illinois.

How many hours of sunshine does Decatur have in January?

In Decatur, the average sunshine in January is 4.1h.

What are the months with the lowest UV index in Decatur?

January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Decatur, Illinois.

What is the UV index intensity in January in Decatur?

In Decatur, Illinois, the average daily maximum UV index in January is 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to the UV radiation.

Average temperature in January
Decatur, IL

Average temperature in January - Decatur, IL
  • Average high temperature in January: 32.9°F

The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (32.9°F).

  • Average low temperature in January: 21.2°F

The month with the highest average low temperature is July (65.7°F).
The coldest month (with the lowest average low temperature) is January (21.2°F).

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Average pressure in January
Decatur, IL

Average pressure in January - Decatur, IL
  • Average pressure in January: 30.15"

The month with the highest atmospheric pressure is January (30.15").
The month with the lowest atmospheric pressure is June (29.92").

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Average wind speed in January
Decatur, IL

Average wind speed in January - Decatur, IL
  • Average wind speed in January: 10.7mph

The windiest month (with the highest average wind speed) is January (10.7mph).
The calmest months (with the lowest average wind speed) are July and August (6.3mph).

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Average humidity in January
Decatur, IL

Average humidity in January - Decatur, IL
  • Average humidity in January: 79%

The month with the highest relative humidity is July (84%).
The month with the lowest relative humidity is October (70%).

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Average rainfall in January
Decatur, IL

Average rainfall in January - Decatur, IL
  • Average rainfall in January: 1.06"

The wettest month (with the highest rainfall) is May (2.01").
The driest months (with the least rainfall) are February and December (0.87").

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Average rainfall days in January
Decatur, IL

Average rainfall days in January - Decatur, IL
  • Average rainfall days in January: 6.3 days

The month with the highest number of rainy days is May (17 days).
The month with the least rainy days is February (5.8 days).

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Average snowfall in January
Decatur, IL

Average snowfall in January - Decatur, IL
  • Average snowfall in January: 1.85"

The month with the highest snowfall is January (1.85").
Months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in January
Decatur, IL

Average snowfall days in January - Decatur, IL
  • Average snowfall days in January: 7.2 days

The month with the highest number of snowfall days is January (7.2 days).
Months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average daylight in January /
Average sunshine in January
Decatur, IL

Average daylight in January / Average sunshine in January - Decatur, IL
  • Average daylight in January: 9.7h

The month with the longest days is June (Average daylight: 15h).
The month with the shortest days is December (Average daylight: 9.4h).

  • Average sunshine in January: 4.1h

The month with the most sunshine is June (Average sunshine: 10.4h).
The month with the least sunshine is January (Average sunshine: 4.1h).

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Average sunshine days in January
Decatur, IL

Average sunshine days in January - Decatur, IL
  • Average sunshine days in January: 19.5 days

The month with the most sunshine days is October (19.8 days).
The month with the least sunshine days is May (11.5 days).

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Average UV index in January
Decatur, IL

Average UV index in January - Decatur, IL
  • Average UV index in January: 2

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

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Average cloud cover in January
Decatur, IL

Average cloud cover in January - Decatur, IL
  • Average cloud cover in January: 56

The month with the most cloud cover is January (Cloud cover 56).
The month with the least cloud cover is September (Cloud cover 29).

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Average visibility in January
Decatur, IL

Average visibility in January - Decatur, IL
  • Average visibility in January: 6mi

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

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