The National Weather Service already has issued extreme heat warnings, watches and advisories across a swath of the Midwest and South.

The peak of this week’s summer heat is going to be Wednesday afternoon to the early evening. A ridge of high pressure has made for increasing warmth and humidity across a huge swath of the Upper Midwest,

The Extreme Heat Watch for northeast Illinois has been replaced with an area-wide Heat Advisory, which now goes into effect for all of Chicagoland at 10 a.m. Wednesday.

The Pensacola area is under a heat advisory for the second day in a row. A cluster of showers and thunderstorms will offer relief on Wednesday.

Heat and oppressive humidity will greatly impact your daily routine this week, and First Alert Weather Impact Days have been issued through Thursday due to the excessive heat.

The National Weather Service office in Mobile, Alabama, issued a heat advisory in Escambia, Santa Rosa and Okaloosa counties between 10 a.m. and 7 p.m. Monday. Heat index values are forecast to reach as high as 109℉ in portions of south central and southwest Alabama, northwest Florida and southeast Mississippi.

The heat index considers the actual temperature and amount of moisture in the air using the dew point or relative humidity.

Humidity in the Chicago area will start to rise Tuesday as an incoming heat wave will bring temperatures in the 90s and heat index levels as high as 115 degrees, the NBC 5 Storm Team said. According to NBC 5 Strom Team Meteorologist Alicia Roman,