One out of every three Americans faced severe weather on Thursday as a prolonged heat wave persisted in the South and Southwest, damaging thunderstorms hit the Central United States and another round of heavy downpours threatened to trigger more flooding in rain-soaked parts of the East Coast.
Some 110 million Americans are affected by an oppressive heat wave that has blanketed a huge swath of the country stretching from Southern California to Miami for most of the month.
It was expected to last through the weekend in the Deep South and Southeast and into next week for the Southwest, the National Weather Service said.
Some 80 million Americans should see temperatures or heat indices above 105 Fahrenheit (40.5 Celsius) at some point in the coming days, with dozens of record high temperatures possible, the service said.
Phoenix, where forecasters expect a high on Thursday of 116 F (46.6 C), is on track to post its 21th straight day with temperatures of 110 F or higher. On Tuesday the city hit its 19th consecutive day above the mark, a new record streak.
Strong thunderstorms ripped through the western Missouri, southern Illinois and northern Kentucky on Thursday morning. The storms produced large hail stones, reportedly the size of ping pong balls, and 60 mph (97 kph) winds.
Similar severe thunderstorms were expected to pop up throughout the day in the U.S. Plains and the Tennessee Valley where a cold front was meeting the hot and humid air to the south.
The storms could cause damaging winds, large hail, tornadoes and flash flooding, the National Weather Service said.
In western Tennessee, about 40,000 homes and businesses remained without power after strong thunderstorms knocked down power lines and trees late on Tuesday and early on Wednesday, according to poweroutage.us.
Northern New York state and Vermont were under a flood watch with scattered yet powerful thunderstorms expected to roll through the area on Friday, a week after heavy rains caused widespread flooding.
Rainfall may exceed more than 1 inch (2.5 cm) per hour, causing flash flooding. Waterways remain high or near record levels and the ground remains saturated from previous storms, the National Weather Service said.