DETROIT – The holidays are over, the air is cold and the skies are gray -- must be January in Metro Detroit.
Along with cold temperatures and short days, heavy cloud cover is a defining feature of winter in the city. January is typically Detroit’s cloudiest month, with skies being overcast or mostly cloudy about 63% of the time.
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Another way to measure cloudiness is percent possible sunshine, which compares how much sun actually shines to how much could shine during daylight hours. In January, Detroit averages around 40% of possible sunshine, meaning clouds block more than half of the daylight.
Detroit’s cloudy January weather is closely connected to its location in the Great Lakes region. Large lakes such as Lake Erie and Lake Michigan release moisture into the air, even during winter. When cold air moves across the lakes, that moisture can form thick, low clouds that linger for days.
Winter storm systems also pass through Michigan more often in January, adding to the cloud cover. Because the sun sits low in the sky during winter, these clouds block a larger portion of available light.
This lack of sunlight matters because it affects how the human body functions. Sunlight helps regulate the body’s internal clock, or circadian rhythm, which controls sleep, energy, and alertness. In January, Detroit already has limited daylight, only about 9 to 10 hours per day. When clouds block much of that light, the brain receives fewer signals that it is daytime, which can lead to tiredness, trouble focusing, and disrupted sleep patterns.
Reduced sunlight can also affect mental health. The American Psychiatric Association reports that about 5% of U.S. adults experience Seasonal Affective Disorder (SAD), a type of depression that often occurs during winter.
Even without SAD, many people notice mood changes. About two in five Americans report feeling worse emotionally in winter. Short, cloudy days can lower motivation and energy, especially in northern cities like Detroit.
Although January’s gray skies are unavoidable, spending time outdoors during daylight hours, staying active, and keeping regular routines can help support mental well-being until brighter days return. If that doesn’t work, hang on and remember spring is just 71 days away!