400 people treated for heat-related illness at Arizona airshow as record temperatures bake the West

Record-breaking temperatures are set to persist on Sunday, as an unusual and potent early-season heat dome continues to bring triple-digit highs to parts of the Western U.S.

In Phoenix, Arizona, temperatures soared to 105 degrees on Saturday, marking the third consecutive day that the mercury surpassed the 100-degree mark. At an airshow in nearby Glendale, more than 400 attendees were treated for heat-related illnesses, with at least 25 individuals requiring hospitalization. U.S. Air Force Brig. Gen. David Berkland reported that most of those affected were children under 12 or individuals over 60, many of whom had pre-existing medical conditions such as heart disease, diabetes, or pregnancy.

Across the West, numerous high-temperature records have been shattered since Thursday, with some areas in the Plains also experiencing record-breaking heat. In Phoenix, the temperature reached 105 degrees on Saturday, tying a March record. Tucson saw temperatures reach 102 degrees, while Las Vegas hit 96 degrees, the second-highest temperature recorded for March. Salt Lake City, Utah, and Denver, Colorado, also set new March highs at 84 and 86 degrees, respectively, on Saturday.

The scorching weather extended into the Midwest and Great Plains, with Omaha, Nebraska, recording 96 degrees, and Wichita, Kansas, and Kansas City, Missouri, each reaching 93 degrees.

Extreme heat warnings remain in effect for parts of southern California, Nevada, and Arizona on Sunday, including cities like Las Vegas, Phoenix, Tucson, and Lake Havasu, Arizona. Phoenix is expected to exceed the 100-degree mark for the fourth consecutive day on Sunday, with Las Vegas and Salt Lake City also likely to break additional daily records.

The hot weather is forecasted to move into the South and the Ohio Valley, where numerous daily records could be broken from California to Texas and the Carolinas, including cities like Sacramento, Las Vegas, Albuquerque, Dallas, Oklahoma City, Memphis, New Orleans, Cincinnati, and Raleigh.

Severe weather is expected in southern Indiana and Pennsylvania on Sunday, with the possibility of damaging winds, large hail, and isolated tornadoes. By late Sunday night, a line of scattered storms is anticipated to stretch from Evansville, Indiana, to Columbus, Ohio, and into State College, Pennsylvania. New York City may also experience thunderstorms, some of which could produce gusty winds and small hail.

In the Plains, millions of people are under red flag fire warnings due to low humidity, warm temperatures, gusty winds, and dry vegetation. While the fire danger is expected to continue on Sunday, conditions are predicted to improve slightly by Monday. In Nebraska and South Dakota, several wildfires are still burning, with crews making progress in battling the Morrill Fire and the Cottonwood Fire.

In Hawaii, after a recent flood event, more rain has brought damaging flooding to parts of the island. A flash-flood warning was issued for Oahu, with reports of damage, water rescues, and road closures. The threat of the Wahiawa Dam failing has diminished, but heavy rain could still pose risks. The heaviest rain has shifted to the island of Molokai, with all Hawaiian islands except Kauai under a flood watch for more heavy rain. Thunderstorms and damaging winds are also possible.

ABC News’ Geoffrey Bansen contributed to this report.