Heat warnings and measures are in effect for 110 million people across 21 states over the holiday season. The coming days could see dangerous and possibly historic heat extremes in the West, with temperatures of up to 115 degrees Fahrenheit (46 degrees Celsius) possible.
The National Weather Service in San Francisco warned yesterday that the heat wave could last 6 to 12 days, making it the longest period of extreme temperatures the Bay Area has seen in at least 18 years.
Several daily heat records were broken on Tuesday and more than 130 records could be set by next Tuesday.
The weather service warned that “an extremely dangerous situation exists as we head into a potentially historic and deadly heat wave.”
The agency added that heat is the leading weather-related cause of death in the U.S. and “it is VERY LIKELY that we will add even more to that statistic if preparations are not taken seriously.”
Extreme heat warnings are in effect for much of California, southern Nevada, and parts of Arizona, Washington and Oregon. An extreme heat warning means potentially life-threatening conditions, “with a high to very high risk for a large segment of the population due to prolonged heat with little to no nighttime lighting.”
According to the weather service, temperatures in the Bay Area had already risen to 77 degrees Fahrenheit by 5 a.m. Wednesday morning, with humidity at 18 percent.
As for the holiday season, the heat index (which measures how warm it feels when humidity is taken into account) could reach between 100 and 115 in the Plains and Southeast on Wednesday.
Little Rock, Arkansas, could see a heat index of 240 degrees Fahrenheit, while Phoenix, Arizona, will reach 240 degrees Fahrenheit on the same scale.
Wednesday and Thursday will be extremely hot and humid from Nashville to New Orleans, but temperatures will cool slightly on Friday.
It’s already been a record year for temperatures. It’s only early July, but Miami has spent more time at or above 105 degrees on the heat index than it did in all of 2019.
The extreme heat brings with it an increased risk of wildfires. About 4 million people, mostly in California, are under Red Flag warnings. The warnings urge people to be careful with open fires — an added risk with the fireworks displays taking place during the holiday season.
There is also a chance of stormy weather in the central US, which could disrupt some holidays.
About 13 million people are at risk for severe storms in the western High Plains and Ohio River Valley. High winds are likely in both areas, along with hail and isolated tornadoes in the region.
On Thursday, 6 million people are at low risk of severe storms across much of Missouri and parts of Kansas and Oklahoma.
A secondary area of ​​storms that could lighten up by the afternoon could be Iowa, where tornadoes are possible. The biggest threat will be damaging winds for cities like Kansas City, Missouri, and Topeka, Kansas.
A low pressure area over the central High Plains and a frontal boundary extending from the lower Great Lakes to the central Plains “could provide the backdrop for some meteorological spectacles,” the NWS said.
Flash flooding is possible between eastern Kansas and the Ohio Valley due to heavy rainfall.
This article was originally published on NBCNews.com
