As intense heat continues to move across the eastern two-thirds of the nation throughout the week, air quality will likely suffer as a result.
The cities plagued most by the heat will be St. Louis, Kansas City, Chicago, D.C. and Philadelphia.
Air quality will deteriorate in these areas, with most of the East and Midwest facing moderate health concern as a result of the air quality.
According to the air quality index at airnow.gov, a moderate health concern means that 'air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.'
Areas of more serious concern include Atlanta, Pittsburgh, St. Louis, Chicago, Detroit, Cleveland and Cincinnati.
These areas have been temporarily deemed unhealthy for particularly sensitive groups. According to airnow.gov, "Members of sensitive group may experience health effects."
The general public is not likely to be affected, the site explains.
It's not a coincidence that poor air quality usually accompanies heat waves.
"When you get a large area of high pressure promoting widespread heat, you also get a large zone of stagnant air," said AccuWeather.com Meteorologist Meghan Evans.
"Smoke and ozone can be trapped in the atmosphere, leading to poor air quality."
For the full story on the heat, click here.
Cooler conditions will move into the Interior Northeast early this week, but the warmth will hold on a little longer along the Interstate-95 corridor.
The air felt like an exceptional 163 F in Bandar Mahshahr, Iran, on Friday and similar or worse conditions will follow.
The stream of moisture into the Southwest is drying out some, so this weekend may not be as wet as the previous few days.
A disturbance will swing across the Midwest and fire a round of severe thunderstorms to end the weekend.
Drenching thunderstorms bring little-to-no relief to drought-stricken areas of the Sunshine State.
With no exact details on where Malaysia Airlines Flight 370 went missing, Indian Ocean currents may have swept one piece of the complicated puzzle to shores on Reunion Island.
Heat wave continues for the following: Abilene - 41 consecutive days of 98 degrees or higher, tied 1952 record. Dallas/Ft. Worth - 41st consecutive day of 100 degrees + El Paso - 51st consecutive day of 100 degrees +
Chicago, IL (1988)
100 degrees -- 7th day of 100 degrees or higher in 1088 -- an all-time record number.
Hurricane Erin crossed central Florida from the east with 50-70 mph wind gusts. 9.06" of rain fell in Melbourne. (An all time 24 hour record).