Wednesday resulted in extreme temperatures over the middle of the nation, but the worst is yet to come into Friday.

The forecast high humidity combined with high temperatures can be a killer combination, leaving the human heat defense mechanism, sweating, unable to keep up.

As this happens, your body temperature climbs, and your heart rate increases; this can be followed by heat stroke. If unchecked, vital organs start shutting down, then you’re done.

Stay hydrated and out of the sun during the late morning and afternoon hours. If possible, get into air conditioning for at least part of the day. Avoid strenuous activity in the sun, during the heat of the day. Don’t overeat, as that also raises body temperature.

Central Plains and Midwest

Intense sunshine and high humidity should make many places uncomfortably, if not dangerously, hot. Most of Kansas, Oklahoma and northern Texas will have temperature readings well over 100 degrees, with many areas even breaking the 105-degree mark and a few spots reaching 110 degrees.

The heat will continue for similar areas on Friday, expanding eastward. Cities such as Chicago, Indianapolis and Madison will break into the 90s Friday.

Expect 100s to stick around in northern Texas, Oklahoma and Kansas through at least Monday, with 90s remaining elsewhere. Temperatures should be well above average in these areas, in some places by 10 degrees or more.

Deep South

High temperatures in the 90s will be recorded across much of the Deep South and northern Plains.

With humidity high across these regions, conditions will still be dangerous despite not reaching the 100-degree mark. These temperatures are expected to stick around through at least Monday, as the weather pattern shouldn’t change

Mid-Atlantic

On Saturday, the heat will make its way east to some of the big East Coast cities, such as Washington, D.C., Baltimore and Philadelphia, just in time for the big holiday weekend. Luckily for the East Coast, humidity should decrease on Monday, making it feel less hot for holiday festivities.

Southwest

The dangerous heat that has been in place for much of the Southwest will continue through the Independence Day weekend into the following week. A change in the weather, however, will come on Sunday, when humidity should increase greatly, causing the heat to feel much worse and creating some widespread thunderstorms. With some places reaching temperatures over 110 degrees and moisture moving into the area, Independence Day will feel sticky and hot compared to normal.