We are in the middle of the dog days of summer, and a major heatwave will continue to broil the eastern two-thirds of the nation through midweek.

A large upper-level ridge of high pressure will be centered over the Deep South today, before shifting to the central Plains on Monday and Tuesday. This high pressure will pump plenty of hot, humid air into the eastern two-thirds of the U.S. during this time. High temperatures will be as much as 15 degrees above the normal for this time of year.

High temperatures will generally peak in the 90s across the central/southern Plains, most of the Mississippi Valley, Midwest, Deep South and Southeast. Widespread areas, however, will see the mercury max out in triple digits in the central/southern Plains, Lower Mississippi Valley and Southeast. Even the Great Lakes, Ohio Valley and Mid-Atlantic will see highs in the lower 90s.

Combine this heat with high humidity and it will feel even hotter! Heat index values for most areas will soar up to 110 degrees, but a few spots could experience heat indices as high as 115 degrees.

Extreme Heat Warnings are in effect across the central Plains into the Upper Mississippi Valley, across the St. Louis metro area, parts of the Ohio Valley and the eastern Carolinas into southeastern Virginia. Otherwise, extensive Heat Advisories are in place throughout the Plains, Mississippi Valley, Midwest, Deep South and most of the Eastern Seaboard.

Many records will be at risk of being broken throughout the Southeast today. Lakeland, Fla., will likely break its record high of 97 degrees set in 1993, with a forecast high of 98 degrees. Punta Gorda, Fla., will have a forecast high of 98 degrees, which would break their record of 98 degrees set in 1956. Hatteras, N.C., Charleston, S.C., Savannah, Ga., and Fort Myers, Jacksonville and Tampa, Fla., will all likely tie their record highs for the day. Meanwhile, Augusta and Macon, Ga., and Tallahassee, Fla., will be a degree or two short of their record high temperatures.

A potent cold front will drop south across the central and eastern U.S. for the second half of the work week. Temperatures will trend closer to average for most areas, though extreme heat could continue in the southern Plains and Southeast.

If you must go outdoors, prepare by staying hydrated and keep a watchful eye for any signs of heat-related illnesses such as heat stroke and heat exhaustion. Wear the right clothing, such as loose-fitting, lightweight and breathable fabrics, and take many breaks within a cool and shaded area.

Make sure to take extra precautions for children and the elderly as they are more susceptible to heat-related illness. Never leave children or animals alone in a locked vehicle as it can become dangerous and potentially fatal. Do not forget to download the WeatherBug app to stay up to date on the latest for this dangerous western heatwave.