Climate and monthly weather forecast
Waukegan, IL

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The climate of Waukegan

Situated in the state of Illinois in the USA, Waukegan experiences a humid continental climate. This climate type, classified as Dfa by the Köppen Climate Classification, is characterized by no dry season and particularly warm summers.

Throughout the year, Waukegan witnesses a broad range of temperatures, with lows falling to 18.3°F (-7.6°C) and highs soaring up to 77.5°F (25.3°C). The coldest month of the year tends to be January, with an average low of 18.3°F (-7.6°C), while July is the hottest, reaching an average high of 77.5°F (25.3°C).

The city also experiences a notable amount of precipitation, with rainfall recorded in every month. The amount of rainfall varies notably, with the smallest volume recorded in December at 0.91" (23mm) and the most significant in both May and August at 2.68" (68mm).

Relatively high humidity of between 75 and 83% is an inherent trait of Waukegan's climate, with the highest levels generally occurring in January and June. While the sun shines in Waukegan throughout the year, the city experiences a higher amount of sunshine in June and July, both sporting a rate of 10.5 hours per day.

The best time to visit Waukegan

Considering the temperature, sunshine, and rainfall, the best time to visit Waukegan is between May and October. During these months, temperatures range from an average low of 48.6°F (9.2°C) to a maximum high of 77.5°F (25.3°C). Additionally, these months witness the most extended daylight hours, ranging from 14.6 hours in May up to 15.2 hours in June, ensuring visitors can make the most of their trip.

The summer months from June to August also bring the highest volume of sunshine to Waukegan, providing an average of 10.5 hours of sunlight per day. Between May and August, rainfall averages around 2.58" (66mm), making it a suitable period for outdoor activities.

The worst time to visit Waukegan

While Waukegan's climate makes it a year-round destination, the colder months from December through February might not be the most comfortable for visitors. During these months, temperatures fluctuate between 18.3°F (-7.6°C) and 30.6°F (-0.8°C), while daylight hours start at 9.1 hours in December and increase to 10.6 hours by February.

Spring weather in Waukegan

Spring in Waukegan, spanning from March to May, is a period of fast transition. Temperatures rise rapidly from an average of 41.2°F (5.1°C) in March to 61.3°F (16.3°C) in May. Daylight hours also witness a noticeable increase from 12 hours in March to 14.6 hours in May. Meanwhile, humidity levels remain relatively consistent, around 78 to 80%.

Summer weather in Waukegan

Summer months from June to August in Waukegan are marked by warm temperatures and abundant sunlight. The average temperature during this period swings relatively consistently, from 70.5°F (21.4°C) in June to 77.5°F (25.3°C) in July, before moderating to 77°F (25°C) in August. The summer season is also characterized by the highest amount of sunlight, averaging 10.5 hours per day.

Autumn weather in Waukegan

The fall season from September to November in Waukegan is marked by a steady decline in temperatures from 70.9°F (21.6°C) in September to 45.1°F (7.3°C) in November. Daylight hours also decline significantly from 12.5 hours in September to 9.8 hours in November. Humidity levels remain moderately high, between 75 and 77% throughout.

Winter weather in Waukegan

Winter in Waukegan, running from December to February, brings the coldest temperatures of the year. During this period, the readings fluctuate between 18.3°F (-7.6°C) and 30.6°F (-0.8°C) on average. Along with this, the duration of daylight reduces to its shortest, with an average of 9.5 hours in December and 10.6 hours by February.

Weather in January

January in Waukegan, Illinois exhibits the ramifications of a harsh winter. Snow falls on an average of 12.4 days with 2.24" (57mm) of accumulation. Freezing temperatures, high humidity, and significant cloud cover dominate the weather pattern. Weather in January »

Weather in February

February ushers in marginally milder conditions compared to its predecessor. Also characterized by winter weather, it's marked by reduced snowfall, slightly higher temperatures, and marginally lesser rainfall. Visibility remains largely the same, despite the slight increase in daylight hours. Weather in February »

Weather in March

March brings about the much-anticipated shift from winter to spring in Waukegan, Illinois. Although the snowfall reduces drastically to 0.79" (20mm), temperatures begin to rise noticeably. It is characterized by increased rainfall, signifying the onset of the April showers. Weather in March »

Weather in April

April marks the beginning of pleasant weather in Waukegan, Illinois. The temperature varies from 38.8°F (3.8°C) to 50.7°F (10.4°C), and rainfall amounts reach their peak with a measurement at 2.44" (62mm). Spring flowers begin to bloom, and the daylight hours increase, further enhancing April's appeal. Weather in April »

Weather in May

May experiences a transition towards consistent summer-like weather in Waukegan, Illinois. The increasing daylight hours make for characteristic long, sunny days. The increasingly warm weather reinvigorates the lush greenery for which the city is known. Weather in May »

Weather in June

June is the prelude to peak summer time in Waukegan, Illinois. With the highest daylight figures peaking at 15.2 hours, it offers long sunny days. Outdoor activities thrive under the expansive blue skies typical of the month. As the summer progresses, the oncoming months bring the highest temperatures of the year, beginning with July. As May transitions into June, Waukegan sees a rise in the average high-temperature, moving from a comfortable 61.3°F (16.3°C) to a pleasant 70.5°F (21.4°C). Weather in June »

Weather in July

July is representative of summer's peak in Waukegan, Illinois. With temperature measurements escalating to an average high of 77.5°F (25.3°C) and a UV index of 6, it's the hottest month of the year. Folks cool off by the lake enjoying the beautiful weather, a tradition enjoyed year after year. Weather in July »

Weather in August

August in Waukegan, Illinois, retains July's high temperatures. While retaining the idyllic summer imagery, a slightly higher average rainfall signifies the onset of autumn in the upcoming months. The illustrious shades of green permeate the city as the lush vegetation thrives. Weather in August »

Weather in September

September is characteristic of the highly awaited fall season in Waukegan, Illinois. The slight decline in temperatures and the reduction in daylight hours mark the change. As the shades of leaves transition from green to golden, it's a wonderfully picturesque month. Weather in September »

Weather in October

October brings a stark contrast to the warmer months with temperatures in Waukegan, Illinois falling more rapidly. Though the fall foliage is a beautiful sight, colder temperatures signal the approach of winter. Cloud cover increases, days shorten, and the need for warmer clothing escalates. Weather in October »

Weather in November

November heralds the onset of winter in Waukegan, Illinois. Rainfall decreases drastically to 1.02" (26mm) while temperatures drop significantly. With a higher probability for snowfall, it's clear that winter is looming. The sharp transition into the frosty December makes for an intriguing climax to the year. As Waukegan, Illinois, enters November, the average high-temperature decreases from the a moderate 58.3°F (14.6°C) of October to a chilly 45.1°F (7.3°C). Weather in November »

Weather in December

December provides a fitting wintry end to the year in Waukegan, Illinois. Increasing cloud cover, reduced daylight hours, and the arrival of snow make for a fitting winter scenery. With an average low temperature at 25.3°F (-3.7°C), it's certainly the time to bundle up. Weather in December »
Updated: Feb 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are the coldest months in Waukegan?

In Waukegan, Illinois, the average lowest temperatures are observed in January, with a high of 27.9°F (-2.3°C) and a low of 18.3°F (-7.6°C).

What is the most humid month in Waukegan?

The most humid month in Waukegan is January, with an average relative humidity of 83%.

How many days does it rain in Waukegan?

In Waukegan, during the entire year, the rain falls for 142.5 days and collects up to 21.5" (546mm) of precipitation.

When does it snow in Waukegan?

Months with snowfall in Waukegan are January through April, October through December.

How much does it snow in Waukegan?

Throughout the year, in Waukegan, there are 45.5 snowfall days, and 9.37" (238mm) of snow is accumulated.

What is the month with the least sunshine in Waukegan?

January has the least sunshine of the year in Waukegan, with an average of 3.7h of sunshine.

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

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

What is the snowiest month in Waukegan?

February is the month with the most snowfall. Snow falls for 9.8 days and accumulates 2.6" (66mm) of snow.

When is Daylight Saving Time (DST) in Waukegan?

On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts in Waukegan, Illinois, 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 in Waukegan?

In Waukegan, Illinois, snow does not fall in May through September.

What is the wettest month in Waukegan?

The months with the most rainfall are June and August, with an average 2.68" (68mm) of precipitation.

When are the longest days in Waukegan?

With an average of 15h and 12min of daylight, June has the longest days of the year.

What are the warmest months in Waukegan?

In Waukegan, Illinois, the peak average temperatures are observed in July, with a high of 77.5°F (25.3°C) and a low of 65.3°F (18.5°C).

What is the month with the most sunshine in Waukegan?

July and August, with an average of 10.5h of sunshine, are months with the most sunshine.

When is the highest UV index in Waukegan?

The months with the highest UV index in Waukegan are July and August, with an average maximum UV index of 6.

What is the least humid month in Waukegan?

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

What is the driest month in Waukegan?

December is the month with the least rainfall in Waukegan, Illinois. Rain falls for 8.1 days and accumulates 0.91" (23mm) of precipitation.

What is the month with the shortest days in Waukegan?

With an average of 9h and 6min of daylight, December has the shortest days of the year in Waukegan, Illinois.

Average temperature
Waukegan, IL

Average temperature - Waukegan, IL

The warmest month (with the highest average high temperature) is July (77.5°F).
The month with the lowest average high temperature is January (27.9°F).

The month with the highest average low temperature is July (65.3°F).
The coldest month (with the lowest average low temperature) is January (18.3°F).

Average pressure
Waukegan, IL

Average pressure - Waukegan, IL

The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

Average wind speed
Waukegan, IL

Average wind speed - Waukegan, IL

The windiest month (with the highest average wind speed) is January (11.9mph).
The calmest month (with the lowest average wind speed) is August (7.3mph).

Average humidity
Waukegan, IL

Average humidity - Waukegan, IL

The month with the highest relative humidity is January (83%).
The months with the lowest relative humidity are October and November (75%).

Average rainfall
Waukegan, IL

Average rainfall - Waukegan, IL

The wettest months (with the highest rainfall) are June and August (2.68").
The driest month (with the least rainfall) is December (0.91").

Average rainfall days
Waukegan, IL

Average rainfall days - Waukegan, IL

The month with the highest number of rainy days is July (17 days).
The month with the least rainy days is February (5.2 days).

Average snowfall
Waukegan, IL

Average snowfall - Waukegan, IL

The month with the highest snowfall is February (2.6").
The months with the least snowfall are May, June, July, August and September (0").

Average snowfall days
Waukegan, IL

Average snowfall days - Waukegan, IL

The month with the highest number of snowfall days is January (12.4 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average daylight / Average sunshine
Waukegan, IL

Average daylight / Average sunshine - Waukegan, IL

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

The months with the most sunshine are July and August (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).

Average sunshine days
Waukegan, IL

Average sunshine days - Waukegan, IL

The month with the most sunshine days is November (16.5 days).
The month with the least sunshine days is July (10.8 days).

Average UV index
Waukegan, IL

Average UV index - Waukegan, IL

The months with the highest UV index are July and August (UV index 6).
The months with the lowest UV index are January and December (UV index 1).

Average visibility
Waukegan, IL

Average visibility - Waukegan, 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).

Waukegan, Illinois, USA

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