Climate and monthly weather forecastJoliet, IL
Climate and monthly weather forecast
The climate of Joliet
Resting in the state of Illinois, Joliet experiences a Humid Continental climate, classified as Dfa according to the Köppen climate classification. Due to this climate, weather conditions in Joliet fluctuate greatly between months, where each of the four seasons are well represented with clear defining characteristics.The city's annual weather parameters depict considerable variations. Temperature ranges fluctuate between a peak of 81.3°F (27.4°C) in July, to a chilling low of 17.4°F (-8.1°C) in January. Humidity, although relatively high throughout the year, peaks at 83% in February, providing some respite in the cold winter month.
On the precipitation front, Joliet records notable rainfall throughout the year, reaching its highest at 4.41" (112mm) in May. Public attention draws to the snowfall patterns, with noticeable snow registering from 1.57" (40mm) in April and wintry highlights in January at 4.33" (110mm).
Visibility remains consistent at 6 miles for most months, with slight variation in January and February. While winds maintain an average speed of 8.9mph (14.3km/h) in December, gusts can reach as high as 14.5mph (23.3km/h) in November.
The best time to visit Joliet
For those wishing to make the most of their visit to Joliet, the months May through to September prove inviting. During this period, temperatures range from a pleasant 70.3°F (21.3°C) to 80.1°F (26.7°C). The sunlight hours peak to 15.1 hours in June, allowing tourists ample time to explore the city in daylight. Despite the high temperatures, humidity is relatively lower compared to other months, hovering between 77% to 80%.The worst time to visit Joliet
January registers as the harshest month to visit Joliet due to the low temperature of 17.4°F (-8.1°C), coupled with high snowfall up to 4.33" (110mm) and reduced daylight of only 9.6 hours. The accompanying winds, averaging 9.5mph (15.3km/h), worsen the cold conditions. Additionally, February's peak humidity of 83% compounded with an average temperature of 20.7°F (-6.3°C) makes the city uninviting for outdoor activities.Spring weather in Joliet
Spring in Joliet runs from March to May, with temperatures increasing from 46.2°F (7.9°C) to 70.3°F (21.3°C). Rainfall escalates during spring, peaking at 4.41" (112mm) in May, being the heaviest rainfall across the year. Despite the increased precipitation, the period also experiences longer daylight hours, reaching 14.5 hours by May's end.Summer weather in Joliet
During the summer months, Joliet experiences its highest temperatures, rising to a high of 81.3°F (27.4°C) in July. Despite being the hottest part of the year, rainfall reduces from June's 4.02" (102mm) to 2.83" (72mm) by August. Sunshine prolongs up to maximum of 15.1 hours in June, dimming slightly to 14.8 hours by July, providing ample visibility throughout the day.Autumn weather in Joliet
Autumn commences in September with temperatures decreasing from 74.7°F (23.7°C) to 47.1°F (8.4°C) by November. Simultaneously, rainfall shows a marked rise in September and October before reducing to 1.69" (43mm) in November. Cloud coverage also shows an increase in November as autumn progresses.Winter weather in Joliet
Wintertime in Joliet, spanning December to February, is typically cold with the lowest temperature dropping to 17.4°F (-8.1°C) in January. Snow curtains the city during this period, peaking at 4.33" (110mm) in January. Daylight hours contract to a minimum of 9.2 hours in December, the shortest throughout the year.Weather in January
The climate in Joliet, Illinois in January manifests the heart of winter characterized by its relative coldness and dampness. This month sees the maximum snowfall with 4.33" (110mm) and registers an average high of 29.3°F (-1.5°C) and a low of 17.4°F (-8.1°C), enumerating the lowest temperatures of the year. Weather in January »Weather in February
The transition to February doesn't denote a significant departure from the winter chill, but a slight increase in temperature is noticeable. February weather reveals average high temperature of 33.4°F (0.8°C), slightly higher than January’s 29.3°F (-1.5°C), yet its 3.7" (94mm) of snowfall is generally lesser. Weather in February »Weather in March
March serves as a bridge in Joliet's climactic shift from winter to spring, marking an increase in temperature and sunlight hours. This month shows a remarkable rise in temperature with an average high of 46.2°F (7.9°C) and a noteworthy reduction in snowfall down to 1.65" (42mm). Weather in March »Weather in April
April is a distinct signal of spring's arrival in Joliet. Although March’s temperate climate extends into April, this month observes the onset of considerable rainfall - up to 3.62" (92mm). Longer daylight hours are enjoyed courtesy of the season, shrinking the prevalence of cloud cover. Weather in April »Weather in May
May in Joliet welcomes warmer weather and the onset of the city's rainiest month with 4.41" (112mm) of rainfall recorded. The change in season is accompanied by a noticeable leap in temperature, bringing longer daylight hours and consequently more sunshine. Weather in May »Weather in June
The month of June in Joliet holds the promise of summer weather blooming vibrantly. With temperatures substantially elevated compared to May, June’s average high reaches 79.2°F (26.2°C) maintaining a warm setting. This period is associated with elongated days, soaking in the maximum amount of sunlight annually. Weather in June »Weather in July
July is characterized as the climax of the summer season in Joliet. Balmy temperatures are the benchmark for July, and a high of 81.3°F (27.4°C) is typically recorded, the year's hottest. Despite the heat, relative humidity remains high throughout the month. Weather in July »Weather in August
August mirrors July in many ways, but with a subtle hint of upcoming autumn. The overall temperature marginally declines from July’s high of 81.3°F (27.4°C) to August’s 80.1°F (26.7°C). Extended sunlight hours and less wind activity continue to mark the weather pattern in August. Weather in August »Weather in September
September is an epitome of a transitional month in Joliet, with summer slowly yielding to the upcoming fall. The temperature drops moderately from August’s 80.1°F (26.7°C) to a comfortable 74.7°F (23.7°C). As autumn nears, daylight hours decrease while mild winds begin to sway, signalling a change in season. Weather in September »Weather in October
October brings about substantial transformations in Joliet's weather, signaling the onset of fall. A further dip is seen in October’s temperature, down to an average high of 61.3°F (16.3°C). This month is subject to lesser rainfall than September, but the declining temperatures result in diminished daylight hours. Weather in October »Weather in November
November in Joliet embraces the full essence of fall with colder temperatures, shorter days, and the possibility of early snowflakes. A palpable drop in temperature to an average high of 47.1°F (8.4°C) is seen, inviting a winter chill. Weather in November »Weather in December
December witnesses the advent of winter once more, closing the year with the second-highest snowfall estimated at 2.4" (61mm). The month’s average high caps at 35.1°F (1.7°C), reinforcing the frosty atmosphere of Joliet winters. Weather in December »Updated: Aug 15, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
January tends to be the coldest month, with temperatures averaging a daily high of 29.3°F (-1.5°C) and a low of 17.4°F (-8.1°C).
In Joliet, during the entire year, the rain falls for 153.6 days and collects up to 32.72" (831mm) of precipitation.
Months with snowfall are January through April, November and December.
The month with the most snowfall is January, when snow falls for 11.9 days and typically aggregates up to 4.33" (110mm) of snow.
In Joliet, during the entire year, snow falls for 38.2 days and aggregates up to 14.61" (371mm) of snow.
With an average of 3.7h of sunshine, January has the least sunshine of the year in Joliet.
January and December, with an average maximum UV index of 1, are months with the lowest UV index.
The most humid month is February, with an average relative humidity of 83%.
February is the month with the least rainfall. Rain falls for 5.7 days and accumulates 1.61" (41mm) of precipitation.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts in Joliet, 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.
May is the month with the most rainfall. Rain falls for 17.8 days and accumulates 4.41" (112mm) of precipitation.
In Joliet, Illinois, snow does not fall in May through October.
June has the longest days of the year, with an average of 15h and 6min of daylight.
The months with the highest UV index are June and July, with an average maximum UV index of 6.
Joliet's temperatures peak on average in July, reaching 81.3°F (27.4°C) at their highest and 64.8°F (18.2°C) at their lowest.
August has the most sunshine of the year, with an average of 9.7h of sunshine.
October is the least humid month, with an average relative humidity of 73%.
December has the shortest days of the year, with an average of 9h and 12min of daylight.
Average temperature
Joliet, IL
The warmest month (with the highest average high temperature) is July (81.3°F).
The month with the lowest average high temperature is January (29.3°F).
The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (17.4°F).
Average pressure
Joliet, IL
- Average pressure in January:
30.12"Hg - Average pressure in February:
30.1"Hg - Average pressure in March:
30.09"Hg - Average pressure in April:
29.95"Hg - Average pressure in May:
29.96"Hg - Average pressure in June:
29.92"Hg
- Average pressure in July:
29.97"Hg - Average pressure in August:
29.98"Hg - Average pressure in September:
30.03"Hg - Average pressure in October:
30.01"Hg - Average pressure in November:
30.1"Hg - 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 (29.92"Hg).
Average wind speed
Joliet, IL
- Average wind speed in January:
9.5mph - Average wind speed in February:
9.4mph - Average wind speed in March:
9.3mph - Average wind speed in April:
9.7mph - Average wind speed in May:
8.3mph - Average wind speed in June:
7.2mph
- Average wind speed in July:
6.2mph - Average wind speed in August:
5.9mph - Average wind speed in September:
6.9mph - Average wind speed in October:
8.5mph - Average wind speed in November:
9.1mph - Average wind speed in December:
8.9mph
The windiest month (with the highest average wind speed) is April (9.7mph).
The calmest month (with the lowest average wind speed) is August (5.9mph).
Average humidity
Joliet, IL
The month with the highest relative humidity is February (83%).
The month with the lowest relative humidity is October (73%).
Average rainfall
Joliet, IL
- Average rainfall in January:
1.85" - Average rainfall in February:
1.61" - Average rainfall in March:
2.09" - Average rainfall in April:
3.62" - Average rainfall in May:
4.41" - Average rainfall in June:
4.02"
- Average rainfall in July:
3.46" - Average rainfall in August:
2.83" - Average rainfall in September:
2.48" - Average rainfall in October:
2.95" - Average rainfall in November:
1.69" - Average rainfall in December:
1.69"
The wettest month (with the highest rainfall) is May (4.41").
The driest month (with the least rainfall) is February (1.61").
Average rainfall days
Joliet, IL
- Average rainfall days in January:
6.8 days - Average rainfall days in February:
5.7 days - Average rainfall days in March:
12.6 days - Average rainfall days in April:
16.3 days - Average rainfall days in May:
17.8 days - Average rainfall days in June:
17.8 days
- Average rainfall days in July:
17.9 days - Average rainfall days in August:
15.8 days - Average rainfall days in September:
12.5 days - Average rainfall days in October:
12.9 days - Average rainfall days in November:
9.4 days - Average rainfall days in December:
8.1 days
The month with the highest number of rainy days is July (17.9 days).
The month with the least rainy days is February (5.7 days).
Average snowfall
Joliet, IL
The month with the highest snowfall is January (4.33").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days
Joliet, IL
- Average snowfall days in January:
11.9 days - Average snowfall days in February:
9.5 days - Average snowfall days in March:
5 days - Average snowfall days in April:
1 days - Average snowfall days in May:
0 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0 days - Average snowfall days in October:
0.2 days - Average snowfall days in November:
2.6 days - Average snowfall days in December:
8 days
The month with the highest number of snowfall days is January (11.9 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight / Average sunshine
Joliet, IL
- Average daylight in January:
9h and 36min - Average daylight in February:
10h and 36min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 24min - Average daylight in May:
14h and 30min - Average daylight in June:
15h and 6min
- Average daylight in July:
14h and 48min - Average daylight in August:
13h and 48min - Average daylight in September:
12h and 30min - Average daylight in October:
11h and 6min - Average daylight in November:
9h and 54min - Average daylight in December:
9h and 12min
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).
- Average sunshine in January:
3h and 42min - Average sunshine in February:
3h and 54min - Average sunshine in March:
6h and 6min - Average sunshine in April:
7h and 30min - Average sunshine in May:
8h and 30min - Average sunshine in June:
9h and 30min
- Average sunshine in July:
9h and 36min - Average sunshine in August:
9h and 42min - Average sunshine in September:
8h and 30min - Average sunshine in October:
5h and 42min - Average sunshine in November:
5h and 6min - Average sunshine in December:
4h and 6min
The month with the most sunshine is August (Average sunshine: 9h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days
Joliet, IL
- Average sunshine days in January:
14.4 days - Average sunshine days in February:
13.8 days - Average sunshine days in March:
14.6 days - Average sunshine days in April:
11.1 days - Average sunshine days in May:
11.6 days - Average sunshine days in June:
10.4 days
- Average sunshine days in July:
10.8 days - Average sunshine days in August:
11.8 days - Average sunshine days in September:
15 days - Average sunshine days in October:
16.5 days - Average sunshine days in November:
18.1 days - Average sunshine days in December:
15.9 days
The month with the most sunshine days is November (18.1 days).
The month with the least sunshine days is June (10.4 days).
Average UV index
Joliet, IL
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover
Joliet, IL
The month with the most cloud cover is January (Cloud cover 60).
The months with the least cloud cover are August and September (Cloud cover 34).
Average visibility
Joliet, IL
The months with the highest visibility are March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are January, February, July and August (5mi).
