Climate and monthly weather forecast
Belleville, IL

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The climate of Belleville

Belleville, a city located in the state of Illinois, USA, enjoys a humid subtropical climate, without a dry season, as indicated by its Köppen climate classification of Cfa. This particular climate type leads to a blend of weather patterns throughout the year.

The city's climatic pattern shows fluctuations in temperature, precipitation, and other climatic parameters. Belleville possesses an annual high temperature oscillating from 37.8°F (3.2°C) in January to a peak of 85.8°F (29.9°C) in July. The low temperatures also diverge widely, with January being the coolest month at 24.8°F (-4°C), and July again being the warmest at 68.4°F (20.2°C).

In terms of precipitation, Belleville experiences rainfall throughout the year with May recording the highest average rainfall of 4.37" (111mm). The least rainfall is recorded in February 1.93" (49mm). Snowfall occurs primarily in the winter months of January and December, each with an average of 2.4" (61mm) and 2.01" (51mm) respectively. Days with snowfall occur from January to March and reappear briefly in November and December.

Belleville boasts regular sunshine year-round, with the longest days in June boasting a considerable 14.8 hours of daylight. The shortest days are in December with an average of 9.5 hours. Year-round humidity levels hover between 71% to 79%.

The best time to visit Belleville

With a varied climate throughout the year, the optimum time to plan a visit to Belleville would be during the transitional months of spring and autumn, when the temperatures are relatively moderate compared to the highs of summer and the lows of winter. The month of May, despite recording the highest rainfall, also promises comfortable temperatures ranging from 57.9°F (14.4°C) to 74.8°F (23.8°C). Similarly, October also offers agreeable temperatures, from 48.9°F (9.4°C) to 66.7°F (19.3°C), along with fairly low rainfall of 2.95" (75mm).

The worst time to visit Belleville

Belleville experiences the coldest temperatures from December to February, where the average high temperature lies between 37.8°F (3.2°C) and 42.4°F (5.8°C), and the lows dropping to between 24.8°F (-4°C) and 27.9°F (-2.3°C). Substantial snowfall during these months further underscores the severity of the winter. The hottest months of July and August, when temperatures peak from 84.6°F (29.2°C) to 85.8°F (29.9°C), also might not be ideal for visitors who are not used to such high temperatures.

Spring weather in Belleville

Spring in Belleville, which extends from March to May, sees a steady rise in temperature from a high of 54.5°F (12.5°C) to a high of 74.8°F (23.8°C), and similarly, lows from 37.9°F (3.3°C) to 57.9°F (14.4°C). April marks the end of snowfall and transitions into a rise in rainfall that peaks at 4.37" (111mm) in May. The average daylight hours extend from 12 hours in March to around 14.3 hours in May, providing ample time for outdoor activities.

Summer weather in Belleville

Summer, extending from June to August in Belleville, is characterized by warm temperatures, high humidity, and ample sunshine. June experiences highs of 83.7°F (28.7°C) and evenings cooling off to 66.6°F (19.2°C), with temperatures peaking in July. Despite the heat, summer records a decrease in rainfall with June witnessing 3.98" (101mm). However, with daylight hours extending up to 14.8 hours, summer offers long, warm days perfect for outdoor recreation.

Autumn weather in Belleville

Autumn in Belleville, spanning September to November, sees a gradual decrease in temperature. September starts with a high of 79.3°F (26.3°C), cooling down to 53.4°F (11.9°C) in November with evenings cooling down between 59.9°F (15.5°C) to 37.8°F (3.2°C). Rainfall reduces from 2.2" (56mm) in September to 2.17" (55mm) in November. The hours of daylight lessen to around 10.1 in November, signifying the onset of winter.

Winter weather in Belleville

Winter in Belleville, beginning in December and ending in February, is marked by low temperatures ranging from 24.8°F (-4°C) to 30.6°F (-0.8°C) at night and 37.8°F (3.2°C) to 42.4°F (5.8°C) during the day. Snow is prominent during these months, contributing to colder weather conditions. The days become shorter with daylight hours reducing to approximately 9.5 hours in December. Despite the low visibility and an increase in cloud cover to 52%, winters in Belleville present a picturesque, snow-covered landscape.

Weather in January

An influx of chill awakens the year in Belleville, Illinois. January relinquishes sunlight sparingly, with relatively fewer daylight hours. The city experiences a noticeable drop in temperature post the festive season, with the average high and low temperatures ranging from 37.8°F (3.2°C) to 24.8°F (-4°C). Weather in January »

Weather in February

The city navigates the chilliness of February, creating a seamless transition from January's cold grip. The snowfall amounts decrease, making way for an increase in rainfall, suggesting a slight ascend toward spring. Wind speeds tend to maintain steadiness and Belleville manages with an average maximum wind speed of 9.9mph (15.9km/h). Weather in February »

Weather in March

March signals the thaw of winters in Belleville as spring hints at an impending arrival. Warming temperatures contribute to creating atmospheric flux, introducing significantly more rainfall in comparison to February. With rising temperature and longer daylight hours, winter's icy breath transcends into a milder spring oscillation. Weather in March »

Weather in April

Spring convincingly demonstrates its presence in Belleville during April, emanating an aura of renewal and growth. The charm of the vernal season graces Belleville and its environs with an array of blossoming plant life. The gradual ascension in temperature becomes erratic, contributing to the prevalence of April showers. Weather in April »

Weather in May

May in Belleville presents weather characterized by mild temperatures and longer days. With a progressive increase in sunshine and daylight hours, May homes in on ideal outdoor conditions. A noticeable surge in average high temperature to 74.8°F (23.8°C) becomes evident, placing May as a significant turning point toward warmer months. Weather in May »

Weather in June

June marks the onset of the summer season in Belleville with temperatures taking a decisive turn toward warmth. A consistent increase in sunlight hours implies a full awakening of nature's bounty. Belleville radiates beneath the summer sun, offering longer daylight hours and excellent visibility for outdoor enthusiasts. Weather in June »

Weather in July

July stands as the epitome of summer in Belleville. Carrying the baton from June, July continues to grace the city with abundant sunshine and culminates in summer's highest average high and low temperatures from 85.8°F (29.9°C) to 68.4°F (20.2°C). Weather in July »

Weather in August

There is a subtle transition to be felt as August unfolds in Belleville. Capping off the last of the high-summer months, August heralds shorter daylight hours yet remains comfortably warm. The city retains a high relative humidity, reinforcing its distinct summertime atmosphere. Weather in August »

Weather in September

September brings a nuanced change to Belleville's weather. As summer waves a warm goodbye, September gently escorts the city into the embrace of fall. The drop in temperatures becomes apparent, with the average high temperature comfortably resting at 79.3°F (26.3°C). Weather in September »

Weather in October

Autumn solidifies its grip on Belleville during the month of October. The season of 'falling leaves' breathes a wave of cultural and scenic transformation, making October a picturesque time in the city. The dwindling warm days succumb to a crisp, cool climate, making way for mellow, autumnal evenings. Weather in October »

Weather in November

November moves Belleville decidedly into more defined fall weather. As sunlight hours continue to dwindle, the city transitions smoothly into cooler weather, typical of the late fall months. Residents can observe a conspicuous decrease in temperature, leading to a need for warmer clothing. Weather in November »

Weather in December

December in Belleville introduces winter's bone-chilling cold, a stark juxtaposition to November's subdued coolness. With cloud cover becoming more prevalent and the daylight receding to the fewest hours, December brings an undeniably wintry feel. Weather in December »
Updated: Aug 29, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What month is the coldest?

Belleville's coldest weather arrives in January, when temperatures average a high of 37.8°F (3.2°C) and a low of 24.8°F (-4°C).

How many days does it rain?

In Belleville, Illinois, during the entire year, the rain falls for 147.1 days and collects up to 35.43" (900mm) of precipitation.

When does it snow?

Months with snowfall in Belleville are January through March, November and December.

When does it snow the most?

The month with the most snowfall in Belleville is January, when snow falls for 7.3 days and typically aggregates up to 2.4" (61mm) of snow.

How many days does it snow?

Throughout the year, there are 21.1 snowfall days, and 8.11" (206mm) of snow is accumulated.

What is the month with the least sunshine?

January has the least sunshine of the year, with an average of 4.5h of sunshine.

What are the months with the lowest UV index?

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

What is the driest month?

The month with the least rainfall is February, when the rain falls for 7.8 days and typically collects 1.93" (49mm) of precipitation.

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.

When it does not snow?

April through October are months without snowfall.

What is the most humid month?

May and July, with an average relative humidity of 79%, are most humid months.

What is the rainiest month?

The month with the most rainfall is May, when the rain falls for 16.4 days and typically aggregates up to 4.37" (111mm) of precipitation.

When is the highest UV index?

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

When are the longest days?

June has the longest days of the year, with an average of 14h and 48min of daylight.

What month has the most sunshine?

June has the most sunshine of the year, with an average of 10.3h of sunshine.

What are the warmest months?

The warmest month is July, with an average high-temperature of 85.8°F (29.9°C) and an average low-temperature of 68.4°F (20.2°C).

What is the least humid month?

October is the least humid month, with an average relative humidity of 71%.

What is the month with the shortest days?

The month with the shortest days is December, with an average of 9h and 30min of daylight.

Average temperature
Belleville, IL

Average temperature - Belleville, IL

The warmest month (with the highest average high temperature) is July (85.8°F).
The month with the lowest average high temperature is January (37.8°F).

The month with the highest average low temperature is July (68.4°F).
The coldest month (with the lowest average low temperature) is January (24.8°F).

Average pressure
Belleville, IL

Average pressure - Belleville, IL

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
Belleville, IL

Average wind speed - Belleville, IL

The windiest month (with the highest average wind speed) is January (9.4mph).
The calmest month (with the lowest average wind speed) is July (5.6mph).

Average humidity
Belleville, IL

Average humidity - Belleville, IL

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

Average rainfall
Belleville, IL

Average rainfall - Belleville, IL

The wettest month (with the highest rainfall) is May (4.37").
The driest month (with the least rainfall) is February (1.93").

Average rainfall days
Belleville, IL

Average rainfall days - Belleville, IL

The month with the highest number of rainy days is May (16.4 days).
The month with the least rainy days is January (6.8 days).

Average snowfall
Belleville, IL

Average snowfall - Belleville, IL

The month with the highest snowfall is January (2.4").
The months with the least snowfall are April, May, June, July, August, September and October (0").

Average snowfall days
Belleville, IL

Average snowfall days - Belleville, IL

The month with the highest number of snowfall days is January (7.3 days).
The months with the least snowfall days are May, June, July and August (0 days).

Average daylight / Average sunshine
Belleville, IL

Average daylight / Average sunshine - Belleville, IL

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).

The month with the most sunshine is June (Average sunshine: 10h and 18min).
The month with the least sunshine is January (Average sunshine: 4h and 30min).

Average sunshine days
Belleville, IL

Average sunshine days - Belleville, IL

The month with the most sunshine days is October (18.3 days).
The month with the least sunshine days is May (12.3 days).

Average UV index
Belleville, IL

Average UV index - Belleville, IL

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 visibility
Belleville, IL

Average visibility - Belleville, IL

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).

Belleville, Illinois, USA

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