Don’t let those sunny conditions fool you. Thursday’s brisk wind brought on another cold-water upwelling along some Lake Michigan beaches. Earlier today, the water temperatures at a handful of the most popular state park beaches had plummeted into the 50s.

Here's what we know. The NWS issued a Beach Hazard statement in Lake, Northern Cook and Central Cook Counties through Friday morning. High wave action and dangerous currents are expected at Lake Michigan beaches with 4-7-foot waves.

Lake Michigan faces high waves and dangerous currents, prompting swimming warnings along Illinois, Indiana, and Michigan beaches.

From algal blooms to harmful bacteria in the water, there are a number of factors that could cause a beach to close.