ST. LOUIS – A heat advisory hits the St. Louis region Sunday with heat index values expected to reach 100 for the first time this year. Dangerous heat is expected to continue into next week as a ridge of high pressure builds over the area.

Nearly 30 eastern Missouri counties and municipalities are under a heat advisory Sunday, including St. Louis City, St. Louis County and most surrounding areas. The current advisory lasts from 11 a.m. to 9 p.m. Sunday.

Throughout Sunday, temperatures will climb into the 90s with increasing humidity. Heat indices will likely climb into the triple digits.

By Monday and Tuesday, we could see heat index readings of 105 to 110 degrees as the actual air temperature hits around 100. Record high temperatures will likely be broken both of these days.

Heat index through Wednesday

On Wednesday, temperatures will still be near 100 degrees and heat indices will still likely be dangerous. There is a chance of a few storms late in the day on Wednesday. Thursday and Friday will still be quite hot, but highs will drop to the lower half of the 90s.

This heat is the biggest of the season so far and will bring an increased risk of heat-related illness so take necessary safety precautions. 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 doing work or exercise 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. Most importantly, listen to your body!