Parts of the Southwest kept feeling like summer Saturday, as extreme heat warnings returned across California and Arizona and sweltering conditions pushed northward into Nebraska just days into spring, according to the National Weather Service forecasts cited by the Associated Press. Temperatures at or above 100 degrees Fahrenheit (37.7 C) were forecast in the Southwest, extending a week marked by record-breaking warmth.

In Arizona, the National Weather Service predicted 100 degrees (37.7 C) in Tucson. Further southwest, the Yuma Desert was headed toward 105 degrees (40.5 C) a day after reaching 112 degrees (43.3 C), a record high for the highest March temperature in the United States, the report said.

The AP report also said two Southern California locations hit 100 degrees Friday. Experts cited in the report said triple-digit days typically arrive by May rather than March.

In the Midwest, the National Weather Service predicted temperatures exceeding 90 degrees (32.2 C) across Nebraska, followed by a “big drop” into the 50s and 60s Sunday, the report said. A red flag warning was posted, a warning flagging a higher risk for wildfires, and the report said parts of Texas also were expected to reach 90 degrees or higher Saturday.

The heat arrived as large wildfire incidents continued in Nebraska. The state Emergency Management Agency said evacuation orders were lifted in areas affected by Nebraska’s Cottonwood and Morrill fires, which the agency said have burned more than 1,200 square miles (3,118 square kilometers) for days but are largely contained. The affected areas are dominated by range and grassland, according to the report.

The Associated Press included accounts from hikers affected by the conditions, including Win Marsh, who said she and her husband returned home early to Utah after hiking Arizona’s trail beginning at the Mexico border. Marsh, 63, said Saturday, “We know our limits,” adding, “We can’t hike when our bodies can’t cool down. There’s no shade out there, and water sources are drying up. … We promised our kids we wouldn’t do sketchy stuff. We’re not out there for a search-and-rescue event.”

Beyond the immediate forecasts, experts said the early-season pattern is likely to persist. The AP report said researchers and meteorologists expect April, May and June to be hotter than normal almost everywhere in the U.S.

World Weather Attribution, an international group of scientists that studies the causes of extreme weather events, said Friday that March’s heat would have been virtually impossible without human-caused climate change. The AP report cited the group’s finding as the basis for that assessment.