After a humid start to the week, Pittsburgh will experience a taste of September by midweek.
Humid air into Tuesday midday will allow showers and thunderstorms to form or move through the area.
However, a strong cool front will cross the region Tuesday afternoon, marking an end to the storm threat and the beginning of a several-day spell of unseasonably cool and less humid air for mid-July.
Nighttime temperatures will dip into the 50s F Tuesday through Thursday. Daytime highs Tuesday into Friday will be in the 70s.
Temperatures of this sort are more common for Pittsburgh during the middle of September.
The Alaskan wood frog, which freezes itself during the harsh winter months, can remain in an extreme frozen state far longer than researchers originally thought.
An area of low pressure will bring a threat of heavy rain and flooding to parts of southern Europe through the middle of the week.
A cold front swinging into the Northeast will bring the threat of severe weather to part of the region on Tuesday afternoon.
The late-season swelter will continue along much of the Atlantic Seaboard through the week as tens of millions head back to school and work.
Tropical Storm Dolly has formed in the southwestern Gulf of Mexico's Bay of Campeche and will continue its northwest path into northeastern Mexico.
A second volcanic eruption occurred on Sunday morning in Iceland in the same area that had one on Friday.
Mecca, CA (1950)
126 degrees - highest ever for U.S. in Sept.
East Coast (1775)
Matecumbe Key, FL (1935)
Labor Day Hurricane hit Florida. Pressure at Matecumbe Key dipped to 26.35"/892.3 mb. Most intense hurricane ever to hit the U.S. with 200-mph wind. Tide of 15 feet; 408 dead.