Sunday was an historically hot day in Orange County.

Santa Ana, at 88 degrees, registered the highest temperature in the continental United States, according to the National Weather Service. And Newport Beach, at 85 degrees, broke a nearly century-old heat record for Dec. 10, sizzling past its previous high of 80 degrees set in 1924.

The Santa Ana heat wave also was the highest Dec. 10 temperature recorded at that station since the National Weather Service began measuring there in 1999. The average high temperature for the date in Santa Ana is 66 degrees.

The Santa Ana winds that have fueled the large wildfires burning in Southern California also are causing the high heat.

“Typically, we get the cool marine air mass that moves in and that keeps us temperate, but the Santa Ana winds come from the opposite direction – the east – and it pushes the cool air back out over the ocean,” said Mark Moede, a meteorologist for the National Weather Service in San Diego.

Moede forecasted that Orange County would remain dry and hot through Friday. He projected that temperatures would hover 10 to 20 degrees above average – meaning in te 70s and 80s.

After last year’s wet and cold winter, the Climate Prediction Center in Washington, D.C. has predicted that Southern California will have an unseasonably warm and dry winter this year – similar to the winters the region experienced two and three years ago. Moede said weather conditions comparable to the ones that caused those dry, sunny winters have returned.

For most of Sunday, the cities of Santa Ana, Fullerton and Long Beach held a three-way tie for hottest location in America – tied at 87 degrees – but Santa Ana continued to warm.

It was the fifth time this year that an Orange County city was the hottest location in America. Fullerton held that distinction twice, hitting 107 degrees on Jan. 29 and Oct. 23.

The coldest place in America on Sunday was Snake River Ranger Station, Wyoming, which was -13 degrees – a full 101 degrees cooler than Santa Ana.