Strong-to-severe thunderstorms will be possible for a widespread area stretching from the Plains across the Ohio and Tennessee River valleys and into the Northeast.

WEATHER RESEARCHERS UNLEASH FLEET OF DRONES THAT SAIL DIRECTLY INTO EYE OF HURRICANE

The possibility of heavy rain with these storms could lead to flash flooding in areas that have already seen too much rain. 

The scorching heat continues to break records from the Southwest and the southern Plains to South Florida, with not a lot of relief in sight. 

Smoke from Canadian wildfires will cause poor air quality for sections of the Midwest, Great Lakes and Northeast. 

In addition, Tropical Storm Calvin in the Pacific will bring heavy rain and tropical storm winds for Hawaii.