Stay out of Lake Michigan, swimmers.
That's the message from the National Weather Service, which issued a beach warning through 9 p.m. Thursday.
The NWS warned that high waves, strong rip currents and overall dangerous swimming are expected throughout the day on beaches along the Illinois and Indiana lakeshores. "Dangerous pounding waves" and life-threatening rip currents" also are likely.
Rip currents are described as powerful channels of water flowing quickly away from shore, often occurring at low spots or breaks in sandbars. The currents can sweep swimmers from shore into deeper water.
The threat will end late Thursday into Friday morning, according to the NWS.
The rest of the day looks warm and clear, models show. Sunshine mixes with scattered clouds, and highs range from the low 70s along the lakefront to the upper 70s inland.
The next chance for rain comes Friday afternoon with a few spotty light showers possible.
The weekend looks dry with highs in the mid-70s.