A groundhog in Punxsutawney saw his shadow yesterday and announced there would be more winter.

But what does a rodent know? Yesterday's high in Pittsburgh was 52 degrees. Six more weeks of ... what winter?

January in Pittsburgh was the eighth-warmest on record and the mildest in 56 years. The average daily temperature was 38 degrees, with the average daily high a balmy 46, according to meteorologist Pat Herald of the National Weather Service.

For Pittsburgh, that's almost tropical.

And the city isn't alone. Higher-than-average temperatures have been recorded across the nation this winter, according to Michael Mann, associate professor at Penn State University and director of the university's Earth System Science Center.

"What's so remarkable is if you talk to people all over the U.S., it's the same story," he said.

He said that usually when one area of the nation is experiencing higher-than-average temperatures, another is bitter cold, as part of the natural "wiggles of the jet stream."

While Dr. Mann said climate change couldn't be directly blamed for the warmer temperatures, he said events are consistent with global warming predictions.

He explained that temperature over the years resembles a bell curve.

"What climate change is doing is shifting the bell curve so that it is centered at a higher value," Dr. Mann said. Because of that shift, the type of warm winter that at one time may have happened once in 100 years will now occur maybe once in 25 years.

"I think we are going to start to see these kinds of events become a lot more common," he said.

Trees leafing, plants sprouting, animals awakening from hibernation, birds migrating and eggs hatching all can be caused by a milder winter and an earlier spring.

But Mr. Herald of the National Weather Service said that you can't take a local or even a national number and say it's global warming.

"It's just a matter of patterns," he said.

While the United States may be experiencing a milder winter than usual, Mr. Herald pointed out, Russia is experiencing record cold.

And starting this weekend, up to Valentine's Day, it looks like it's going to get colder, he said.

Perhaps the groundhog was onto something.