MINNEAPOLIS (WCCO) — The high temperature on Friday is expected to be 98 degrees.

But it’s going to feel closer to 105 degrees with all the humidity.

So, what causes humidity? Good Question.

“Humidity is water in the air,” Mike Augustyniak, WCCO’s Director of Meteorology, said. “It’s evaporated, you can’t see it.”

The moisture in the air can come from a number of places, including large bodies of water, nearby plants or a saturated ground.

In Minnesota’s case, some of the moisture is coming all the way from the Gulf of Mexico, where the sun evaporates the water from air. Strong wind then pushes it all the way up north.

Humidity can also come from the water plants release during photosynthesis. It’s a process called evapotranspiration, but many people know it as corn sweat.

“If you get a breeze from the south, where the corn knee-high by the Fourth of July, that will raise how much humidity is in the air,” Augustyniak said.

Significant moisture in the air can happen after major rains. For example, two weeks ago, the ground in the Twin Cities metro area was saturated following thunderstorms. The heat then evaporated that water. In that case, the ground was acting like a big lake.

Some people find it hard to handle the humidity because it makes it harder for the human body to cool through sweating. Sweat doesn’t evaporate as quickly when there’s lots of moisture in the air that essentially traps the sweat in.

Heather Brown

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