Monthly weather forecast and climate
Chicago, IL

An aerial view of the city of Chicago in Illinois, on the shores of Lake Michigan, with a superb view of the sandy beach of Oak Street
An aerial view of the city of Chicago in Illinois, on the shores of Lake Michigan, with a superb view of the sandy beach of Oak Street
Chicago has a hot-summer humid continental type of climate (Köppen climate classification Dfa) with hot and humid summers and cold winters.
It lies in northeastern Illinois, on the southwestern shores of Lake Michigan in the Great Lakes region, and is part of the Midwestern United States. Lake Michigan moderates the climate of Chicago with cooler summers and warmer winters compared to other places in Illinois. Chicago, the Windy City, stretches on the continental divide at the confluence of the Great Lakes and Mississippi river waters. The city is at an average elevation of 176 meters above sea level with naturally flat topography.

Chicago summers tend to be hot as the average high temperature touches 85°F (29.4°C) at the peak of July. High temperatures reach 90°F (32.2°C) for a few days, while they rarely cross 100°F (37.8°C).
Winters are cold with the average low temperature of 17°F (-8.3°C) in January, and even daily highs are sometimes below freezing of 32°F (0°C). The breezes from Lake Michigan have a localized cooling effect on the immediate lakefront neighborhoods; dense fog in the city is a common effect of the breeze during the winter.

Humidity averages 70% over the year, which makes the weather muggy. The sunshine reaches the ground in Chicago for an annual 2400 hours, and generally, 84 days have clear skies during the year. Annual precipitation of 36" (914.4mm) occurs within 124 rainy days and summers are a little wetter than the other seasons. Snowfall is in the range of 36" (914.4mm), with an average of 28 snowy days during the year.

The highest officially recorded temperature in Chicago is 105°F (40.6°C) at Midway Airport on July 24, 1934, while the lowest recorded temperature was -27°F (-32.8°C) at O'Hare Airport on January 20, 1985.
The best time to visit Chicago is in spring from March to May and in autumn from September to October, although visitors throng the city from March to November.
Spring is wet and warm, while autumn is pleasant with warm days and cold nights. Summer is usually the peak tourist season, but the temperatures are a bit higher than the shoulder seasons, and visitors throng the city in large numbers.

December to February is the worst time to visit Chicago in the cold of winter.
Heavy snowfall occurs during the winter months, and the snowpack becomes at least 3" (76.2mm) thick. Snowstorms rarely occur in Chicago, but the temperatures drop below 10°F (-12.2°C) for one-fourth of the nights during winter, and few even drop to 0°F (-17.8°C) and below. Summer crowds disperse during the cold months in vast numbers.

Chicago is amongst the top ten safest cities in the United States, with few incidences of tornadoes, floods, wildfires, or earthquakes. However, spring and summer are prone to thunderstorms, and an average of 38 days during the year witness thunderstorms. Snowstorms rarely occur during the winter, but a single day of 10" (254mm) of snow occurs once in a few years.

The average temperatures are in the frigid zone of 17°F (-8.3°C) to 31°F (-0.6°C) - most of the days remain below the freezing temperature of 32°F (0°C), while nights range in the -10°F (-23.3°C) to 10°F (-12.2°C). Weather in January »

February sees cold winter temperatures in the average range of 20°F (-6.7°C) to 35°F (1.7°C). Majority of the nights register below 20°F (-6.7°C), while a few days touch 40°F (4.4°C). Weather in February »

March is windier in Chicago at the beginning of spring, but the temperatures are warmer than winter. Most days register above 40°F (4.4°C), while a few ranges between 50°F (10°C) to 60°F (15.6°C). Weather in March »

The average temperatures are in the 39°F (3.9°C) to 59°F (15°C) with most of the days above 40°F (4.4°C) and nights above freezing. Weather in April »

May is a warm spring month in Chicago with pleasant temperatures in the average range of 48°F (8.9°C) to 70°F (21.1°C). Days are routinely above 50°F (10°C), and some even register 80°F (26.7°C). Weather in May »

June is the sunniest month in Chicago with days spanning the average range of 58°F (14.4°C) to 80°F (26.7°C). Many days register temperatures above 85°F (29.4°C), a few cross 90°F (32.2°C), while 100°F (37.8°C) is rare except during a heatwave. Weather in June »

July is the hottest month of the year in Chicago as the temperatures cook up to 95°F (35°C). The average high temperature is 84°F (28.9°C), while the average low temperature is 63°F (17.2°C). Weather in July »

The average temperatures are in the 63°F (17.2°C) to 82°F (27.8°C) zone - days are over 70°F (21.1°C) most of the time but rarely touch 90°F (32.2°C); nights seldom drop below 50°F (10°C). Weather in August »

The weather is usually calm with warm temperatures that average in the 54°F (12.2°C) to 75°F (23.9°C) range. A few days cross 80°F (26.7°C), but it is rare to record temperatures above 90°F (32.2°C). Weather in September »

The average temperatures are in the 43°F (6.1°C) to 62°F (16.7°C) zone - most days are above 50°F (10°C), while a few nights may drop below freezing. Weather in October »

The average temperatures in the city are between 32°F (0°C) to 48°F (8.9°C), while Lake Michigan shore areas tend to be a little warmer. Weather in November »

December is the start of the cold winter in Chicago with the first substantial snowfall. The average temperatures are in the freezing 21°F (-6.1°C) to 35°F (1.7°C) range. Weather in December »

What is the coldest month in Chicago?

January is the coldest month, with an average high-temperature of 31.5°F (-0.3°C) and an average low-temperature of 18.1°F (-7.7°C).

How many days does it rain in Chicago?

In Chicago, during the entire year, the rain falls for 123.1 days and collects up to 39.1" (993mm) of precipitation.

When does it snow in Chicago?

January through April, October through December are months with snowfall in Chicago.

How many days does it snow in Chicago?

Throughout the year, in Chicago, there are 26.7 snowfall days, and 37.1" (942.3mm) of snow is accumulated.

When does it snow the most in Chicago?

January is the month with the most snowfall. Snow falls for 8.1 days and accumulates 11.5" (292.1mm) of snow.

When is the lowest UV index in Chicago?

Months with the lowest UV index in Chicago, Illinois, are January and December, with an average maximum UV index of 1.

What is the driest month in Chicago?

The month with the least rainfall in Chicago, Illinois, is February when the rain falls for 8.8 days and typically collects 1.9" (49.3mm) of precipitation.

What is the month with the coldest ocean in Chicago?

February is the month with the coldest seawater in Chicago, Illinois, with an average ocean temperature of 36.9°F (2.7°C). For swimming, this is considered very dangerous and immediately life-threatening. Total loss of breathing control instantly occurs, and clear thinking becomes almost impossible. A specialized swimsuit is obligatory to minimize thermal loss.

What is the least humid month in Chicago?

With an average relative humidity of 64.1%, May is the least humid month in Chicago.

What is the wettest month in Chicago?

May is the month with the most rainfall. Rain falls for 11.4 days and accumulates 4.1" (104.9mm) of precipitation.

When are the longest days in Chicago?

The month with the longest days is June, with an average of 15.2h of daylight.

What month has the most sunshine in Chicago?

With an average of 10.4h of sunshine, June has the most sunshine of the year.

What is the month with the highest UV index in Chicago?

Months with the highest UV index in Chicago, Illinois, are June and July, with an average maximum UV index of 9.

What is the warmest month in Chicago?

The warmest month in Chicago is July, with an average high-temperature of 84.2°F (29°C) and an average low-temperature of 67.5°F (19.7°C).

What month is the ocean warmest in Chicago?

With an average ocean temperature of 73.9°F (23.3°C), August is the month with the warmest seawater. A person's cold intolerance, with sunshine, wind, and air temperature, are essential factors for enjoying swimming in 73.9°F (23.3°C) water. (FYI: The Olympic swimming competition requires a water temperature between 77°F (25°C) and 82.4°F (28°C).)

What is the most humid month in Chicago?

With an average relative humidity of 75.5%, December is the most humid month in Chicago.

What is the month with the shortest days in Chicago?

With an average of 9.2h of daylight, December has the shortest days of the year in Chicago.

What is the month with the least sunshine in Chicago?

December has the least sunshine of the year, with an average of 3.4h of sunshine.
Average temperature - Chicago, IL
Average humidity - Chicago, IL

The month with the highest relative humidity is December (75.5%).
The month with the lowest relative humidity is May (64.1%).

Average rainfall - Chicago, IL
Average rainfall days - Chicago, IL

The month with the highest number of rainy days is May (11.4 days).
The month with the lowest number of rainy days is September (8.2 days).

Average snowfall - Chicago, IL
Average snowfall days - Chicago, IL

The month with the highest number of snowfall days is January (8.1 days).
Months with the lowest number of snowfall days are May, June, July, August and September (0 days).

Average sea temperature - Chicago, IL

The best month for swimming (with the highest average sea temperature) is August (73.9°F).
The coldest month (with the lowest average sea temperature) is February (36.9°F).

Average daylight / Average sunshine - Chicago, IL
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