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.
Snow will swing across parts of the central and northern Plains to the Upper Midwest as November ends and December begins.
As millions head home from their Thanksgiving ventures the weather may cause trouble on the roads and at the airports from the southern Appalachians to the central Rockies on Sunday.
Tropical Rainstorm Sandra will continue to bring the risk of flooding rainfall to portions of western Mexico into Saturday night.
The reprieve from heavy rain across southern India will not last with the threat for flooding downpours set to return for the final days of November.
The first widespread ice storm of the season will slowly diminish over parts of the southern and central Plains, but areas of slippery travel will continue into Sunday morning.
An active storm track across northern Europe will bring more wind and rain across Germany into the new week.
Lake Superior (1960)
A severe lake storm along the north shore of Lake Superior: waves 20-40 feet high, wind gust to 73 mph. Floods and waves caused structural damage.
Goodland, KS (1983)
19 inches of snow on the ground with drifts of up to 8 feet.
Sixty cities tied or established new record high temperatures for the date.