This is the look at the current heat index values which are updated hourly.
On Sunday, showers and thunderstorms affect much of the area. The rainfall in the soil is evaporating today and leading to higher dewpoints near the surface. The end-result being higher heat index values this afternoon.
An Excessive Heat Warning is in effect for Eastern Oklahoma and the Fort Smith area which Heat Advisories are in effect across NW Arkansas.
Through 9pm Monday, heat indices could be as high as 120 in the Fort Smith area and closer to 110 in NW Arkansas.
A break in the heat could arrive later this week with an increase in clouds and slightly higher rain chances.