Climate and monthly weather forecast
Romeoville, IL

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Weather in January

January, the same as December, in Romeoville, Illinois, is a freezing cold winter month, with an average temperature varying between 17.1°F (-8.3°C) and 28.8°F (-1.8°C). With average temperatures fluctuating between a high of 28.8°F (-1.8°C) and a low of 17.1°F (-8.3°C), January stands out as the coldest month. Weather in January »

Weather in February

February, the last month of the winter in Romeoville, is an icy month, with an average temperature varying between 19.9°F (-6.7°C) and 32.5°F (0.3°C). February commences with an average high-temperature of a cold 32.5°F (0.3°C), showing little deviation from January's 28.8°F (-1.8°C). Weather in February »

Weather in March

March, the first month of the spring in Romeoville, is a chilly month, with temperature in the range of an average high of 45.7°F (7.6°C) and an average low of 32°F (0°C). The transition to March introduces an increase in the average high-temperature, shifting from a cold 32.5°F (0.3°C) in February to a chilly 45.7°F (7.6°C). Weather in March »

Weather in April

April is a refreshing spring month in Romeoville, Illinois, with temperature in the range of an average high of 57°F (13.9°C) and an average low of 41°F (5°C). The arrival of April brings a change in Romeoville's weather, with average high-temperatures moving from March's chilly 45.7°F (7.6°C) to a mild 57°F (13.9°C). Weather in April »

Weather in May

The last month of the spring, May, is an agreeable month in Romeoville, Illinois, with an average temperature varying between 52.3°F (11.3°C) and 69.4°F (20.8°C). With the onset of May, Romeoville experiences a temperature shift, with the average high-temperature moving from a refreshing 57°F (13.9°C) in April to an agreeable 69.4°F (20.8°C). Weather in May »

Weather in June

The first month of the summer, June, is a warm month in Romeoville, Illinois, with an average temperature ranging between max 78.6°F (25.9°C) and min 61.3°F (16.3°C). In Romeoville, stepping into June brings a temperature increase, moving up from May's pleasant 69.4°F (20.8°C) to a moderately hot 78.6°F (25.9°C). Weather in June »

Weather in July

July, like June, in Romeoville, Illinois, is another warm summer month, with an average temperature varying between 81.9°F (27.7°C) and 65.7°F (18.7°C). July is the month that records the highest temperatures, with averages ranging from a high of 81.9°F (27.7°C) to a low of 65.7°F (18.7°C). July's heat index is computed to be a hot 87.8°F (31°C). Weather in July »

Weather in August

The last month of the summer, August, is also a moderately hot month in Romeoville, Illinois, with temperature in the range of an average high of 80.2°F (26.8°C) and an average low of 63.9°F (17.7°C). The advent of August brings an average high-temperature of a still warm 80.2°F (26.8°C), exhibiting minor difference from the previous month. Weather in August »

Weather in September

September, the first month of the autumn in Romeoville, is still a warm month, with temperature in the range of an average low of 57.4°F (14.1°C) and an average high of 74.3°F (23.5°C). A subtle change in temperatures is noted as August gives way to September, with average highs reducing from 80.2°F (26.8°C) to a still moderately hot 74.3°F (23.5°C). Weather in September »

Weather in October

October, like September, is a moderate autumn month in Romeoville, Illinois, with an average temperature varying between 45.5°F (7.5°C) and 60.6°F (15.9°C). With the onset of October, Romeoville experiences a modest temperature adjustment, with the average high-temperature receding from a warm 74.3°F (23.5°C) in September to a mild 60.6°F (15.9°C). Weather in October »

Weather in November

November, the last month of the autumn in Romeoville, is also a frosty month, with an average temperature ranging between min 33.4°F (0.8°C) and max 46.6°F (8.1°C). Arrival of November comes with a reduction in the average high-temperature, falling from a refreshing 60.6°F (15.9°C) in October to a frosty 46.6°F (8.1°C). Weather in November »

Weather in December

December, the first month of the winter in Romeoville, is still a cold month, with temperature in the range of an average low of 24.6°F (-4.1°C) and an average high of 34.7°F (1.5°C). December's onset brings a slight change in high-temperatures, falling from a frosty 46.6°F (8.1°C) in November to a cold 34.7°F (1.5°C). Weather in December »
Updated: Aug 15, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are the coldest months?

Romeoville's coldest month, January, registers temperatures that range from a high of 28.8°F (-1.8°C) to a low of 17.1°F (-8.3°C).

What is the most humid month?

January and February, with an average relative humidity of 83%, are most humid months.

How much does it rain?

In Romeoville, during the entire year, the rain falls for 145.4 days and collects up to 22.83" (580mm) of precipitation.

When does it snow?

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

What is the snowiest month?

January is the month with the most snowfall in Romeoville. Snow falls for 12.1 days and accumulates 3.11" (79mm) of snow.

How many days does it snow in Romeoville?

Throughout the year, in Romeoville, there are 44.4 snowfall days, and 11.93" (303mm) of snow is accumulated.

What is the month with the least sunshine?

January has the least sunshine of the year, with an average of 3.8h of sunshine.

When is Daylight Saving Time (DST)?

On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from CST to CDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from CDT to CST.

What is the wettest month in Romeoville?

May is the month with the most rainfall. Rain falls for 16.4 days and accumulates 2.83" (72mm) of precipitation.

When it does not snow?

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

When are the longest days?

June has the longest days of the year, with an average of 15h and 6min of daylight.

What are the months with the highest UV index?

June through August, with an average maximum UV index of 6, are months with the highest UV index in Romeoville.

What time of the year is the hottest?

The highest temperatures are recorded in July, with averages reaching a high of 81.9°F (27.7°C) and a low of 65.7°F (18.7°C).

What is the month with the most sunshine?

The months with the most sunshine are July and August, with an average of 9.9h of sunshine.

What is the least humid month?

With an average relative humidity of 73%, October is the least humid month in Romeoville.

What is the driest month?

December is the month with the least rainfall. Rain falls for 7.1 days and accumulates 1.06" (27mm) of precipitation.

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 month with the lowest UV index?

The month with the lowest UV index is December, with an average maximum UV index of 1.

Average temperature
Romeoville, IL

Average temperature - Romeoville, IL

The warmest month (with the highest average high temperature) is July (81.9°F).
The month with the lowest average high temperature is January (28.8°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 (17.1°F).

Average pressure
Romeoville, IL

Average pressure - Romeoville, 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).

Average wind speed
Romeoville, IL

Average wind speed - Romeoville, IL

The windiest month (with the highest average wind speed) is January (9.7mph).
The calmest month (with the lowest average wind speed) is August (6mph).

Average humidity
Romeoville, IL

Average humidity - Romeoville, IL

The months with the highest relative humidity are January and February (83%).
The month with the lowest relative humidity is October (73%).

Average rainfall
Romeoville, IL

Average rainfall - Romeoville, IL

The wettest month (with the highest rainfall) is May (2.83").
The driest month (with the least rainfall) is December (1.06").

Average rainfall days
Romeoville, IL

Average rainfall days - Romeoville, IL

The month with the highest number of rainy days is July (18.1 days).
The month with the least rainy days is February (4.9 days).

Average snowfall
Romeoville, IL

Average snowfall - Romeoville, IL

The month with the highest snowfall is January (3.11").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days
Romeoville, IL

Average snowfall days - Romeoville, IL

The month with the highest number of snowfall days is January (12.1 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average daylight / Average sunshine
Romeoville, IL

Average daylight / Average sunshine - Romeoville, IL

The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 12min).

The months with the most sunshine are July and August (Average sunshine: 9h and 54min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).

Average sunshine days
Romeoville, IL

Average sunshine days - Romeoville, IL

The month with the most sunshine days is November (18.4 days).
The month with the least sunshine days is July (9.3 days).

Average visibility
Romeoville, IL

Average visibility - Romeoville, IL

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

Romeoville, Illinois, USA

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