SAN FRANCISCO (KPIX) — A National Weather Service forecaster is issuing an extraordinary warning: stay off Bay Area beaches when the big waves arrive late this weekend.

“This is not the day that you want to send little Johnny down to the water or little Jane to go build sand castles down at the water’s edge,” said Brian Garcia, warning coordination meteorologist for the National Weather Service.

Garcia said a Pacific storm will generate large waves more than 20 feet tall but some waves could get as high as 60 feet Sunday night through Monday morning.

Read more on CBS San Francisco.