It's the warmest Christmas Eve ever in Philadelphia.

The National Weather Service said the mercury at Philadelphia International Airport had reached 71 degrees by early Thursday morning, and is expected to rise even higher throughout the day.

That bested the previous record for Dec. 24 of 64 degrees, which was set in 2014 and 1990.

The record is likely to climb: Forecasters are expecting temperatures to reach the mid 70s in Philadelphia today, said Sarah Johnson, a meteorologist in the weather service's Mount Holly office.

Those temperatures could lead to another warmest-ever mark. The current record high for any date in December in Philadelphia stands at 73 degrees.

"So that's another record we'll be keeping an eye on today," Johnson said.

Other places in the region, including Allentown, Atlantic City, Trenton and Wilmington have also set Christmas Eve record highs.

Along with the warm air, the region could see unusual Christmas Eve thunderstorms later Thursday. Some heavy rain and strong winds are possible.

In Philadelphia, it's the second consecutive day of record-warm temperatures.

Wednesday's high of 70, reached at 10:53 p.m., set the record for Dec. 23.

The previous record high for the date was 66 degrees and set in 1990.

Other record highs tied or set Wednesday include 65 degrees in Allentown, 65 degrees in Atlantic City and 67 degrees in Reading.