Other hikers were rescued as record temperatures topped 110 degrees.
“We are all experiencing rather extraordinary conditions,” Gov. Gavin Newsom said after losing over 200,000 acres to fires fueled by extreme heat and lightning.
A statewide heat wave increases risk of new blazes erupting.
A heat wave across the American Northeast and Southeast subjected cities to record-breaking temperatures on back-to-back days.
Extreme heat over Western Europe would have been "extremely unlikely without climate change," scientists say.
The Paris area hit 108.3 degrees Fahrenheit, beating the previous record of 104.8 F set in 1947.
U.S. beaches may pose a public health threat due to high amounts of fecal bacteria.
Many places facing excessive heat this weekend have no air conditioning, with cities opening shelters for people to cool off.
The current wave of sweltering temperatures and humidity is a preview of life in a warming world.
More than 100 local heat records are expected to fall Saturday, according to the National Weather Service.