400 people were treated for heat-related illnesses at the Arizona Air Show as temperatures soared to record highs in the West

Record temperatures are expected to continue Sunday as a rare and powerful early-season heat dome led to triple-digit highs in some parts of the western U.S.

As temperatures soared to 105 degrees on Saturday in Phoenix, Arizona, the third straight day the weather topped the 100-degree mark, authorities said more than 400 people attending an air show in nearby Glendale were treated for heat-related illnesses.

At least 25 people attending the Luke Days air show at Luke Air Force Base were overcome by hot weather and had to be hospitalized for various heat-related illnesses, said U.S. Air Force Brig. Gen. David Birkeland said at a news conference on Saturday, according to the ABC affiliate KNXV In Phoenix.

The majority of people treated were under 12 or over 60, and many also had “pre-existing medical conditions such as heart disease, diabetes or pregnancy,” Birkeland said.

Dozens of locations across the West have broken high temperature records since Thursday, and some areas in the Plains also saw record lows.

The temperature in Phoenix reached 105 degrees for the third straight day on Saturday, setting the record for March. In Tucson, temperatures rose to 102 on Saturday. The temperature in Las Vegas, Nevada, reached 96 degrees on Saturday, the second-highest temperature there for March after the record high of 97 degrees set on Friday.

Elsewhere in the West, Salt Lake City, Utah, and Denver, Colorado, set new highs for March when they reached 84 and 86 degrees, respectively, on Saturday.

The hot weather also extended across the Midwest and Great Plains. Omaha, Nebraska, recorded 96 degrees on Saturday, while Wichita, Kansas, and Kansas City, Missouri, both reached 93 degrees.

Extreme heat warnings remain in effect for parts of Southern California, Nevada and Arizona on Sunday, including Las Vegas, Phoenix, Tucson and Lake Havasu in Arizona.

Phoenix will likely exceed the 100-degree mark again on Sunday, the fourth straight day the city is expected to exceed that temperature. Las Vegas and Salt Lake City could also see additional daily records through Monday.

The hot weather is expected to continue moving into the South and Ohio Valley, where dozens of daily records could be broken from inland California to Texas and the Carolinas, including in the cities of Sacramento, Las Vegas, Albuquerque, Dallas, Oklahoma City, Memphis, New Orleans, Cincinnati and Raleigh.

Severe weather awaits in southern Indiana and Pennsylvania

Some severe storms are possible for southern Indiana and most of Pennsylvania later Sunday and into Sunday night and may include damaging winds and large hail. Isolated tornadoes are also possible in part of Ohio, the northern part of West Virginia, and southwestern Pennsylvania.

By late Sunday night, a line of scattered storms will likely extend from Evansville, Indiana, to Columbus, Ohio, and into State College, Pennsylvania.

New York City could also see thunderstorms, some strong enough to produce gusty winds and possibly small hail.

A serious fire weather threat in the plains

Millions of people across the Plains received fire warnings Sunday due to low humidity, warm temperatures, gusty winds and dry vegetation. The fire danger is expected to continue on Sunday before improving slightly through Monday.

Meanwhile, several wildfires are still burning north in Nebraska and South Dakota.

Nebraska firefighters have made significant progress battling the Morrill Fire, the largest wildfire in the state’s history. The fire, which has burned more than 640,000 acres across multiple counties in western Nebraska, was 98% contained as of Saturday night, according to Nebraska Emergency Management Agency.

Another major wildfire in Nebraska, the Cottonwood Fire in the south-central part of the state, had burned nearly 130,000 acres and was 94% contained Saturday evening, according to the Nebraska Emergency Management Agency.

More devastating floods in Hawaii

After a devastating flood event more than a week ago during which parts of Hawaii recorded rainfall in feet, more rain is causing devastating and impactful flooding across parts of the island.

A flash flood warning went into effect Saturday due to potentially life-threatening flooding on Oahu and the potential failure of the Wahiawa Dam. There were several reports of damage, water rescues and road closures due to flooding.

The risk of a Wahiawa Dam collapse has eased as water levels gradually fall, but any heavy pockets of rain could cause waters to rapidly rise and reactivate the threat.

The heavy rains shifted eastward, with the island of Molokai under a flash flood warning on Sunday.

All of the Hawaiian Islands except Kauai remain under a flood watch through Sunday due to more heavy rainfall. Mostly heavy rain is expected on the Big Island and Maui, but other islands will see some showers and perhaps some isolated heavy pockets of rain.

Thunderstorms are possible at times, which may include damaging winds.

ABC News’ Jeffrey Bahnsen contributed to this report.