BARRIE, ONT. -- Crowds of sunbathers hit the beach in Wasaga Beach on Tuesday as temperatures climb to over 30 C.

Environment Canada is reporting humidex values in the high 30s to low 40s all week long.

A heat warning is in effect for most of Southern Ontario, including Simcoe County and surrounding areas.

Extreme heat can pose a risk to young children, pregnant women, seniors, those with chronic illnesses, or anyone working outdoors.

The weather agency is forecasting slightly cooler weather by the weekend, but warns, "there is considerable uncertainty."

The heat and humidity are driving many to area beaches, as overcrowding continues to be a significant concern.

The Town of Wasaga Beach recently decided to close the sand-covered portion of Beach Drive from 3rd Street to Spruce Street to try and reduce the crowds.

The town has gone a step further by installing snow fencing to block access to the beach, but most other beach areas inside provincial park boundaries remain open.