Over 20 million people in the mid-Atlantic face the threat of severe storms Thursday, while California braces for “record-setting heat” this weekend that is expected to be even more intense than the heat wave that gripped the region in mid-August and contributed to massive, destructive wildfires.
Another 4 million people are under flash flood watches in parts of the South and Midwest.
“From a hazards perspective, it is the Desert Southwest and throughout California’s Great Valley that stand out most with record breaking high temps likely this weekend and into early next week,” the National Oceanic and Atmospheric Administration said Wednesday afternoon.
About 44 million people are under excessive heat watches and warnings that go into effect Friday across the Southwest and West Coast, with high temperatures expected to possibly reach up to 104 to 117 degrees in cities like Phoenix and Las Vegas and up to 95 degrees in San Diego.
Record-setting heat and dry weather could “envelope” much of the West, the National Weather Service said. More than 100 daily record-high temperatures will likely be set, including several all-time record highs. The high temperatures will begin Friday and go through Monday.
In Los Angeles, daytime highs away from the coast are expected to range from 100 to 115 degrees. “It is not recommended to spend any extended period outside during the heat of the day,” the weather service said.
The heat will also intensify the threat of wildfires, which firefighters in the state are already battling in what is one of the most active fire seasons in California’s history. More than 7,000 blazes have torn through some 1.4 million acres, fueled in part by dry conditions.
Climate change will make heat waves like this longer, more intense, and last later into the summer.
In the mid-Atlantic, there is a risk of severe storms Thursday, including for Philadelphia, Baltimore, and Washington, D.C. Tornadoes are possible, with the threat greatest in the corridor between Washington and Baltimore.
The flash flood watches cover parts of Kentucky, Indiana, Ohio and West Virginia. Cities in the flood zone include Louisville, Cincinnati and Charleston.
Heavy rain in the Ohio Valley is leading to flash flood concerns around Louisville, and more rain is forecast Thursday night.
In the Caribbean, Nana made landfall as a hurricane overnight on the coast of Belize before it was downgraded back to a tropical storm. It will continue to impact parts of Belize, Mexico, Honduras and Guatemala on Thursday with heavy rain and gusty winds. Maximum rainfall of 8 to 12 inches in isolated areas is expected to cause dangerous flash flooding.