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The National Weather Service warns of another hot day across the St. Louis area Tuesday.

Forecasters expect Tuesday will be the second day in of a four-day stretch with a heat index that could reach 100 degrees plus.

A heat advisory is in effect from noon Tuesday until 7 p.m. Thursday for St. Louis city and the counties of St. Louis, Jefferson, St. Charles, St. Clair, Madison and Monroe.

Higher-than-normal temperatures in the low to mid 90s combined with high humidity means it could feel as hot as 101 for a heat index.

The Weather Service says heat and humidity can cause heat stress during outdoor exertion or long exposure.