A compact storm system will throw a final blast of dangerous heat and unbearable humidity through the Ohio Valley and the East Coast`s Interstate 95 corridor. Even better, the near-record heat spell for the Missouri Valley and Mid-South will be corralled by a cold front`s arrival tonight.

A sharp eastward sweeping cold front diving out of the Plains and into the Middle Mississippi Valley will team up with a massive bubble of high pressure in the Tennessee Valley to squeeze out one final punch of near-record heat from the Missouri and Ohio valleys into the Mid-South today. Even the East Coast`s Interstate 95 corridor will get in on the Midwest`s surplus of July heat today and Friday.

The relief arrived first in the east-central Plains and Middle Mississippi Valley on Wednesday. Even at the expense of severe weather, gone are widespread 90s and 100s instead replaced by much more tolerable 70s and 80s from South Dakota to Kansas and Iowa today. Unfortunately, eastern Missouri and Arkansas into Ohio won`t share in the same luck until Friday. The mercury will soar well into the 90s and 100s today.

The northern track of compact low pressure from the Great Lakes into southern New England will mean dangerous heat will be whisked from the Missouri Valley to the East Coast`s Interstate 95 corridor in one fell swoop. The good news is it will only be a brief stay, but the bad news is temperatures will climb close or even break the 100-degree barrier from Columbia, S.C., to Baltimore today; middle to upper 90s will be the rule to end the work week.

Heat Advisories and Excessive Heat Warnings stretch from parts of eastern Oklahoma arcing northwestward to northern Ohio, with a separate area lining the Interstate 95 corridor between southern Georgia and northern New Jersey. St. Louis, Paducah, Ky., Cincinnati and Cleveland, Nashville, Tenn., Philadelphia, Baltimore, Washington, D.C., Raleigh, N.C., and Savannah, Ga., are all included. Throw in high humidity, and the heat index, will top out a toasty 110 to 113 degrees for many locations.

The break in the extreme heat will come at a price from the Northeast all the way to the Missouri Valley today. A strong cold front will deliver a blow of potentially destructive thunderstorms, while it will be a bit more subtle for the Mid-Atlantic on Friday.

Gone will be widespread 90s and triple-digits, replaced by seasonable mid-summer 80s and lower 90s. Even a few upper 70s will sneak into the Midwest and Middle Mississippi Valley as high pressure brings refreshing Canadian air as far south as Iowa, and from northern Illinois to southern Michigan.

Stay hydrated by drinking plenty of water. Make sure to check on at-risk groups, including pets, young children and the elderly. If you must be outdoors for any length of time, take these preventative measures when dealing with such dangerous heat.

Be sure to keep WeatherBug active to receive the latest weather in your neighborhood and get the latest updates anywhere on Twitter.

What do you think of this story?
Click here for comments or suggestions.