More sweltering heat and flash flooding are expected across the nation

A flash-flood threat continued on Sunday from Tennessee to West Virginia as rounds of heavy rain and scattered slow-moving thunderstorms swept across parts of the Midwest and South.

Flood watches remained in effect on Sunday afternoon for several large cities, including Nashville, Lexington, Kentucky, and Charleston, West Virginia. 

Slow-moving thunderstorms in southern West Virginia were causing flash flooding in Huntington, West Virginia, and surrounding areas.

Severe thunderstorms are also possible on Sunday afternoon across parts of the Carolinas and eastern Georgia, including the cities of Charlotte, Charleston, and Savannah, Georgia. Strong winds and damaging gusts are possible in the area.

The severe weather on Sunday follows catastrophic flooding in Missouri over the weekend that prompted hundreds of water rescues, including more than 160 teenagers at Camp Taum Sauk in Reynolds County, officials said.

In Crawford County, Missouri, a missing woman, identified as Faith Gregory, was found dead on Saturday about 2 miles downstream from her home in Huzzah Creek, according to the county sheriff's office.

Extreme heat is impacting parts of the West and northern Plains.

The other big weather story is the extreme heat enveloping parts of the West and northern Plains on Sunday and stretching into the beginning of the week. Daily high temperature records are being threatened on Sunday from Utah and Montana to Minnesota through Monday.

Hot and dry conditions are also fueling elevated to critical fire weather conditions across parts of the Northwest on Sunday afternoon. Heat alerts have been posted from southern California to Montana to Minnesota. 

Extreme heat warnings were issued on Sunday afternoon from Utah to eastern Montana and into Minnesota, including Salt Lake City; Billings, Montana; Bismarck, North Dakota; and Duluth, Minnesota.

Daily high temperature records are being threatened from Utah and Montana to Minnesota through Monday.

Temperatures were topping 100 degrees across much of the Intermountain West on Sunday afternoon and rose above 110 degrees in parts of Montana and Wyoming.

On Sunday, multiple cities in the West, from Utah to Montana, experienced their hottest temperatures on record.

The preliminary high temperature in Salt Lake City was 109 degrees. This breaks the previous all-time record high of 107 degrees, previously set in 1960, 2002, 2021, and twice in 2022. Temperature records for the city go back to 1874.

Billings reached a preliminary high temperature of 111 degrees on Sunday afternoon, shattering the previous all-time high of 108 degrees set on July 14, 2002.

In Miles City, Montana, the temperature rose to a preliminary high of 115 degrees on Sunday afternoon, also shattering its previous all-time high of 111 degrees set on June 26, 2012.

Monsoon thunderstorms could hit Arizona

In southern Arizona, a few monsoon thunderstorms could also turn severe later on Sunday, producing strong wind gusts with the potential to cause damage and prompt blowing dust that could reduce visibility for drivers on roadways.

Heat shifts to the east

On Monday, the heat is expected to shift east to the Dakotas and the Midwest. The high temperature on Monday in Fargo, North Dakota, is expected to be near 100.

If the temperature reaches 100 degrees in International Falls, Minnesota, on Monday, it will not only smash the daily record high of 93 set on July 13, 1983, but it will be the first 100-degree day for the city in more than a century.

The last time the temperature in International Falls hit the triple digits was on July 22, 1923, when it reached an all-time high of 103.

The combination of extreme heat, very dry conditions, and gusty winds was increasing fire danger across parts of the Northwest, including parts of Washington and Oregon. More than two-thirds of the West is experiencing drought conditions of varying intensity. 

Comfortable conditions continue across the Northeast

Meanwhile, residents across the Northeast were enjoying mostly sunny skies and comfortable temperatures on Sunday afternoon, which are expected to continue into Monday.

But by mid-week, the hot temperatures in the West and Plains are expected to move into the Northeast.

Afternoon high temperatures are expected to reach the 90s from Washington, D.C., to Philadelphia, New York City and up to Boston on Tuesday. The high temperatures in the Northeast are expected to be accompanied by high humidity, which will make it feel hotter.

In the Southeast, dangerous heat and humidity continue for parts of the region; however, some of the impacted areas are beginning to see some heat relief, which will be even more noticeable on Monday.

Heat advisories remain in effect on Sunday across parts of Florida, Georgia and the eastern Carolinas, including the cities of Miami, Savannah and Charleston.

Heat indices in South Florida could make it feel 105 to 110 degrees in Miami and Fort Lauderdale.

While hot and humid conditions are a typical part of summer in the Southeast, the compounding effect of consecutive hot and humid days and nights with no relief could create a dangerous situation.