ST. LOUIS – A heat advisory has been issued for the city of St. Louis and several surrounding counties, though storm chances will keep building in the region through Friday evening.

The heat advisory is in effect from noon to 8 p.m. Friday. Throughout Friday, temperatures will climb into the 90s with increasing humidity. Heat indices will likely climb into the triple digits.

Counties under the heat advisory in Missouri include St. Louis County, Franklin, Gasonade, Jefferson and Osage. In Illinois, Monroe and St. Clair counties are also part of the advisory.

St. Louis weather from FOX 2 Meteorologist Linh Truong

Scattered storms are most likely for St. Louis City and the Metro East counties from 4 p.m. to 8 p.m. Storms could also develop early Friday afternoon north of the I-70 corridor.

The heat is expected to be the most intense for the St. Louis region since mid-June. Beacuse of that, there’s an increased risk of heat-related illness, so take necessary safety precautions if you head outdoors. Wear light-weight clothing, drink plenty of water, and avoid strenuous activity. If you do have to work outdoors, take a lot of breaks in the air conditioning, if possible, or shade.

Also if possible, avoid working or exercising outdoors during the hottest part of the afternoon. It’ll be best to get out early in the morning or later in the evening as temperatures fall.