More record highs possible in Southwest, southern Plains, South Florida: Tuesday forecast
Heat will remain persistent across much of the U.S. this week as the nation's sweltering summer continues, according to Monday's forecast from the National Weather Service.
The NWS reports more record-breaking highs are possible from the Southwest into the southern Plains and across South Florida as excessive heat warnings and heat advisories are in effect.
"Over the next several days, nearly all of the Lower 48 will have above average temperatures," the NWS said.
The area between the Northern Rockies to the Pacific Northwest will be the exception, where a cold front will produce below average temperatures.
As US heat wave spreads: Arizona counts the dead: 18 confirmed, dozens more suspected
As of midday Tuesday, more than 46 million Americans were under heat alerts. At least 18 heat-related deaths have been confirmed in the Phoenix area, while an additional 69 deaths are suspected of being heat-related as of July 15, according to a letter from Arizona Gov. Katie Hobbs to the state's utility companies.
US heat index map
Severe rainfall expected for the northern Plains, Midwest, Mid-Atlantic
Active thunderstorms, isolated flash floods and other severe weather was forecast until dawn Tuesday from the northern Plains into the Mid-Atlantic region, according to the NWS. By Wednesday, the frontal boundary causing this will impact the Midwest.
Air quality to worsen in upper Mississippi Valley, Great Lakes
Ongoing Canadian wildfires are not done worsening air quality in the U.S. The upper Mississippi Valley into the Great Lakes and Ohio Valley are next to see air quality alerts for the next few days as persistent western smoke moves southeast, the NWS forecasts.
US air quality map
Northern Great Basin and northern Rockies face fire threat
Even with below average temperatures across the region, parts of the northwestern U.S. could see the risk of fire weather. An inland moving cold front, dry conditions, lower humidity levels and gusty winds will further elevate the critical fire weather threat across the northern Great Basin and northern Rockies.