A weather warning for heat and humidity has been issued.

ST. LOUIS – The 5 On Your Side weather team has issued a severe weather warning for heat and humidity Monday through Thursday.

The National Weather Service has decided to upgrade the heat advisory for the St. Louis metropolitan area from a heat warning to an extreme heat warning. This marks the first extreme heat advisory of the summer for the St. Louis metropolitan area, effective Monday afternoon through Thursday evening.

In addition, a heat warning has been issued for Missouri for all areas outside of St. Louis starting at 1 p.m. Monday. The heat warning also applies to the Illinois side of the river starting at 1 p.m. Tuesday.

The combination of high humidity, high temperatures and light winds will result in dangerous heat index levels. Afternoons and early evenings will feel like 100 to 110 degrees and nights will remain very warm, increasing the risk of heat-related illness.

There is a chance of showers and thunderstorms, but the chance of rain seems lower, so the prospect of much relief from the hot and humid weather is less.

Heat can take a toll on your body. The effects of heat are cumulative and several days of these sweltering temperatures can affect your body.

Remember to check on your neighbors, especially the elderly who may be hesitant to use the air conditioning. Drink plenty of fluids – preferably water – and try to use the air conditioning as often as possible.

Avoid strenuous activities during afternoon heat peaks. Wear light, light-colored clothing and avoid the sun if possible.