Climate and monthly weather forecast
DeKalb, IL

Weather in January

January, like December, is a freezing cold winter month in DeKalb, Illinois, with an average temperature varying between 15.1°F (-9.4°C) and 27°F (-2.8°C). With an average high-temperature of 27°F (-2.8°C) and an average low-temperature of 15.1°F (-9.4°C), January is the coldest month. Weather in January »

Weather in February

The last month of the winter, February, is another freezing cold month in DeKalb, Illinois, with temperature in the range of an average high of 31.1°F (-0.5°C) and an average low of 18.1°F (-7.7°C). In February, the average high-temperature is almost the same as in January - a still freezing cold 31.1°F (-0.5°C). Weather in February »

Weather in March

The first month of the spring, March, is a frosty month in DeKalb, Illinois, with an average temperature fluctuating between 30.2°F (-1°C) and 44.6°F (7°C). In DeKalb, the average high-temperature in March rises from a freezing cold 31.1°F (-0.5°C) in February to a frosty 44.6°F (7°C). Weather in March »

Weather in April

April is a moderate spring month in DeKalb, Illinois, with temperature in the range of an average low of 39.9°F (4.4°C) and an average high of 56.7°F (13.7°C). In April, the average high-temperature rises from a frosty 44.6°F (7°C) in March to a mild 56.7°F (13.7°C). Weather in April »

Weather in May

May, the last month of the spring in DeKalb, is a pleasant month, with an average temperature varying between 68.7°F (20.4°C) and 51.4°F (10.8°C). In May, the average high-temperature increases from a mild 56.7°F (13.7°C) in April to an agreeable 68.7°F (20.4°C). Weather in May »

Weather in June

The first month of the summer, June, is a warm month in DeKalb, Illinois, with an average temperature fluctuating between 60.1°F (15.6°C) and 77.7°F (25.4°C). In DeKalb, the average high-temperature in June increases from an agreeable 68.7°F (20.4°C) in May to a moderately hot 77.7°F (25.4°C). Weather in June »

Weather in July

July, the same as June, is another warm summer month in DeKalb, Illinois, with an average temperature fluctuating between 63.1°F (17.3°C) and 80.2°F (26.8°C). The warmest month is July, with an average high-temperature of 80.2°F (26.8°C) and an average low-temperature of 63.1°F (17.3°C). Weather in July »

Weather in August

The last month of the summer, August, is another warm month in DeKalb, Illinois, with an average temperature ranging between max 78.4°F (25.8°C) and min 61.2°F (16.2°C). In DeKalb, the average high-temperature in August is essentially the same as in July - a still moderately hot 78.4°F (25.8°C). Weather in August »

Weather in September

The first month of the autumn, September, is also an agreeable month in DeKalb, Illinois, with an average temperature fluctuating between 54.5°F (12.5°C) and 73°F (22.8°C). In DeKalb, the average high-temperature in September marginally drops from a warm 78.4°F (25.8°C) in August to a pleasant 73°F (22.8°C). Weather in September »

Weather in October

October, like September, is a moderate autumn month in DeKalb, Illinois, with an average temperature ranging between max 59.9°F (15.5°C) and min 44.1°F (6.7°C). In October, the average high-temperature drops from a pleasant 73°F (22.8°C) in September to a moderate 59.9°F (15.5°C). Weather in October »

Weather in November

The last month of the autumn, November, is another chilly month in DeKalb, Illinois, with an average temperature ranging between max 45.3°F (7.4°C) and min 32°F (0°C). In DeKalb, the average high-temperature in November significantly decreases from a mild 59.9°F (15.5°C) in October to a frosty 45.3°F (7.4°C). Weather in November »

Weather in December

The first month of the winter, December, is still a cold month in DeKalb, Illinois, with temperature in the range of an average low of 23°F (-5°C) and an average high of 33.1°F (0.6°C). In DeKalb, Illinois, the average high-temperature in December decreases from a chilly 45.3°F (7.4°C) in November to a wintry 33.1°F (0.6°C). Weather in December »
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FAQ

What is the coldest month in DeKalb?

The coldest month is January, with an average high-temperature of 27°F (-2.8°C) and an average low-temperature of 15.1°F (-9.4°C).

What are the most humid months in DeKalb?

The months with the highest humidity are January and July, with an average relative humidity of 85%.

How many days does it rain in DeKalb?

Throughout the year, there are 152.6 rainfall days, and 32.09" (815mm) of precipitation is accumulated.

When does it snow in DeKalb?

January through May, October through December are months with snowfall.

What is the snowiest month in DeKalb?

January is the month with the most snowfall. Snow falls for 11.8 days and accumulates 5.55" (141mm) of snow.

How many days does it snow in DeKalb?

Throughout the year, in DeKalb, there are 44.3 snowfall days, and 17.87" (454mm) of snow is accumulated.

What is the month with the least sunshine in DeKalb?

With an average of 3.6h of sunshine, January has the least sunshine of the year.

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

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

What is the driest month in DeKalb?

February is the month with the least rainfall in DeKalb, Illinois. Rain falls for 4.7 days and accumulates 1.65" (42mm) of precipitation.

When is Daylight Saving Time (DST) in DeKalb?

On Sunday, March 12. 2023, at 2:00 am, Daylight Saving Time starts in DeKalb, Illinois, and the time zone changes from CST to CDT. Daylight Saving Time ends Sunday, November 5. 2023, at 2:00 am, and the time zone reverts from CDT to CST.

What are the least humid months in DeKalb?

The months with the lowest humidity are April and October, with an average relative humidity of 75%.

What is the rainiest month in DeKalb?

May is the month with the most rainfall in DeKalb, Illinois. Rain falls for 18.3 days and accumulates 4.37" (111mm) of precipitation.

When it does not snow in DeKalb?

In DeKalb, snow does not fall in June through September.

When are the longest days in DeKalb?

June has the longest days of the year in DeKalb, with an average of 15h and 11min of daylight.

What are the months with the highest UV index in DeKalb?

The months with the highest UV index in DeKalb, Illinois, are June and August, with an average maximum UV index of 6.

What is the warmest month in DeKalb?

With an average high-temperature of 80.2°F (26.8°C) and an average low-temperature of 63.1°F (17.3°C), July is the warmest month in DeKalb, Illinois.

What month has the most sunshine in DeKalb?

With an average of 9.6h of sunshine, July has the most sunshine of the year in DeKalb, Illinois.

What is the month with the shortest days in DeKalb?

The month with the shortest days in DeKalb is December, with an average of 9h and 11min of daylight.

Average pressure
DeKalb, IL

Average pressure - DeKalb, IL

The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

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Average wind speed
DeKalb, IL

Average wind speed - DeKalb, IL

The windiest month (with the highest average wind speed) is April (10mph).
The calmest month (with the lowest average wind speed) is August (6.2mph).

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Average humidity
DeKalb, IL

Average humidity - DeKalb, IL

The months with the highest relative humidity are January and July (85%).
The months with the lowest relative humidity are April and October (75%).

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Average rainfall
DeKalb, IL

Average rainfall - DeKalb, IL

The wettest month (with the highest rainfall) is May (4.37").
The driest month (with the least rainfall) is February (1.65").

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Average rainfall days
DeKalb, IL

Average rainfall days - DeKalb, IL

The month with the highest number of rainy days is May (18.3 days).
The month with the least rainy days is February (4.7 days).

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Average snowfall
DeKalb, IL

Average snowfall - DeKalb, IL

The month with the highest snowfall is January (5.55").
The months with the least snowfall are June, July, August and September (0").

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Average snowfall days
DeKalb, IL

Average snowfall days - DeKalb, IL

The month with the highest number of snowfall days is January (11.8 days).
The months with the least snowfall days are June, July, August and September (0 days).

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Average daylight / Average sunshine
DeKalb, IL

Average daylight / Average sunshine - DeKalb, IL

The month with the longest days is June (Average daylight: 15h and 11min).
The month with the shortest days is December (Average daylight: 9h and 11min).

The month with the most sunshine is July (Average sunshine: 9h and 36min).
The month with the least sunshine is January (Average sunshine: 3h and 36min).

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Average sunshine days
DeKalb, IL

Average sunshine days - DeKalb, IL

The month with the most sunshine days is November (17.2 days).
The months with the least sunshine days are June and July (10.3 days).

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Average visibility
DeKalb, IL

Average visibility - DeKalb, IL

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

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