Which months give vitamin D from the sun in Chicago?

March to October. For the rest of the year the UV index in Chicago stays below 3 on most days, even at noon.

Vitamin D today

Is there vitamin D in Chicago today?

In Chicago the skin makes vitamin D while the UV index reaches 3: today that runs from 10:00 to 17:00. At the best moment about 7 minutes with an average skin type and a quarter of the body uncovered is enough for roughly 1000 IU.

Vitamin D window10:00–17:00

In the sun, at the best moment7 minutes

Sunrise06:08

Sunset19:38

Clear-sky figures: cloud lowers the UV index and lengthens the time needed.

Why tomorrow is not the same

The window moves with the height of the sun, which changes every day, and with the ozone column over Chicago, which varies with the season. It is not one fixed fact about the city: it runs much longer in some months than in others, and at high enough latitudes there are months when it never opens.

See the Chicago vitamin D guide

Sun and vitamin D in Chicago: common questions

What time should you get sun in Chicago today?: Between 10:00 and 17:00: that is the stretch where the UV index reaches 3 in Chicago, the minimum at which skin makes vitamin D. At the best moment about 7 minutes with an average skin type and a quarter of the body uncovered is enough for roughly 1000 IU.
What time are sunrise and sunset in Chicago today?: Today the sun rises at 06:08 and sets at 19:38 in Chicago, with 13 h 30 min of daylight. Most of that light does nothing for vitamin D: only the stretch where the UV index reaches 3 counts.
Which months give vitamin D from the sun in Chicago?: March to October. For the rest of the year the UV index in Chicago stays below 3 on most days, even at noon.