Close your windows, and put on your catcher’s mitt!

Upstate New York is being thrashed by thunderstorms and baseball-size hail — and the wild weather may be headed toward the Big Apple on Tuesday evening.

“TAKE COVER NOW! Move to a basement or an interior room on the lowest floor of a sturdy building,” the National Weather Service said in a weather alert to upstate areas as storms capable of producing tornadoes moved in.

“Avoid windows. If you are outdoors, in a mobile home, or in a vehicle, move to the closest substantial shelter and protect yourself from flying debris.”

Huge hailstones were seen around Ulster County, while a tornado was spotted in Sullivan County, according to AccuWeather.

The National Weather Service has issued a severe thunderstorm watch across New York and the tri-state area until 11 p.m., with a more serious severe thunderstorm warning for Yonkers, Paterson, NJ, and Waterbury, Conn., until 5 p.m.