They suffered minor injuries in Bensalem Township in a tornado that destroyed a car dealership and hit a trailer park, police said.
The Bootleg Fire in Oregon and the Beckwourth Complex Fire in California have burned more than 900 square miles combined.
Forecasters predicted 10 to 14 inches of rain and wind up to 60 mph.
More cities were inundated and crops destroyed as the severe weather spread northwards, with Xinhua news reporting direct economic losses of $189 million.
Doctors in Washington state used human body bags filled with ice and water to rapidly cool the sickest patients affected by record heat last month.
Wildfires rage across 13 states as smoke swirls across the country creating hazy skies along the Eastern Seaboard from Toronto to Washington, D.C.
Erratic winds and parched Oregon forests added to the dangers for firefighters on Monday as they battled the largest wildfire in the U.S., one of dozens burning across several Western states.
A rafting group was camping on the Colorado River when monsoonal rain hit.
The torrential rain has been called a “1 in 100-year event,” said Kathryn Prociv, a meteorologist for NBC News.
June’s record-breaking heatwave was the final ingredient needed for explosive wildfire growth. Fire experts say things could still get much worse.
Storms brought torrential rain that caused rivers to burst their banks and sent torrents of water sweeping through cities and villages in Germany, Belgium and elsewhere across the region.
The Bootleg Fire in Oregon will likely become the first 200,000-acre wildfire of 2021. In the East, up to a foot of rain put parts of Pennsylvania under water.
Nearly 30 million people remained under heat alerts Sunday in the West, where at least 10 states were forecast to hit record triple-digit temperatures.
They died while responding to the Cedar Basin Fire near the Prescott National Forest: "Our hearts are heavy tonight," the Bureau of Land Management said.
The 116-degree high at Las Vegas' airport, which resulted in flights delayed and canceled, was one shy of the city's all-time record of 117.