Dear Tom,
When does the lake start freezing in the Chicago area?
— Amit Jhingran, Chicago
Dear Amit,
The onset of ice formation in the Chicago area on extreme southern Lake Michigan is highly variable and dependent on the severity of the winter season. When an early-season cold wave delivers a prolonged period of sub-freezing temperatures, ice formation can begin as early as mid-December, but in more typical winters, it may not begin to form until late January or early February.
In the mildest winters or winters where temperatures frequently fluctuate from below to above freezing, ice may not form at all. Checking the last 10 winters, the earliest that ice has formed was in mid-December 2013, when temperatures remained well below freezing from Dec. 6-16 during a cold snap that included three days when the mercury plunged to zero or below.
When does the lake start freezing in the Chicago area?

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Lake Michigan almost froze in the Winter of 1993-94
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UPDATE: Ice Storm Warning canceled, Winter Weather Advisory issued
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Winter Weather Advisory for freezing rain mixed at times with sleet and snow, spreading over most of the Chicago area Tuesday
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Winter Weather Advisory for freezing rain starting tonight into Thursday for most counties along and north of I-88 and west/north of Chicago
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Winter Weather Advisory for Chicago area in effect early Monday
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Winter Weather Advisory for snow, ice Chicago area-wide Wednesday
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Winter Weather Advisory issued for Monday; snow, rain could cause icy road conditions
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A wintry mix Wednesday, highs in the 30s
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Winter Weather Advisory for freezing rain discontinued
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How can there be fog when the temperatures are so cold?
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Freezing rain could mean slippery Monday morning commute
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Canceled flights, delayed trains and icy roads as winter storm moves east
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Winter Weather Advisory until 9AM CST Tuesday for most of the Chicago area