Spring equinox has arrived (today, officially)! Someone better tell winter.

The vernal equinox may have arrived, but it sure doesn’t feel like spring in many parts of the country. When is winter going to take the hint and vamoose?

J. David Ake/AP
A jogger runs along the Potomac River on a foggy Thursday morning in Washington. The Northern Hemisphere celebrates the first day of spring Thursday, an event marked by the vernal equinox.

Spring has sprung! At least that’s what the calendar says. However, it could be nearly a month before temperatures fully catch up to the calendar in many parts of the country, according to long-term forecasts.

“It looks like we are going to have a 2-3 week stretch where there’s far more chilly days than warm ones,” says Accuweather meteorologist Mark Paquette.

He does have some consolation for the winter-weary, though.

“Even though we have this extended period of cool weather expected – and I do expect it to be chilly – it’s not going to be like we are locked in the freezer for three weeks at a time,” Mr. Paquette says. “Though the three-week stretch will average quite a bit below normal, we’ll be able to sneak in some normal to above normal days here and there.”

Paquette expects that spring will truly set in around the second week of April and could rapidly give way to more summer-like conditions.

The late warm up isn't actually all that unusual.

As many Northeasterners and Midwesterners know, snow in April is never entirely out of the question.

In New England, the now-fabled April Fools’ Day blizzard buried Boston in two feet of snow, shuttering schools, businesses, and much of the usually weather-hardy public transit system in 1997.

Denver catches an average of 5.6 inches of snow in April, The Weather Channel’s Tom Niziol reports.

Last year, four major wintry storms swept across the Northwest, the High Plains, and the Heartland during the month of April, Mr. Niziol said.

The good news is that it is much more difficult for cold temperatures to persist after the vernal equinox, Accuweather’s Paquette says.

While the equinox technically has more to do with astronomy than meteorology – it’s the day that the sun is positioned most directly over the equator – the amount of solar energy that the Northern Hemisphere receives in coming weeks will not allow bitter cold air masses to build up as frequently as they did a month or two ago, he says.

As the Northern Hemisphere begins to tilt closer toward the sun, there will be more days when it feels even warmer than thermometer readings, he says.

While there is hope in the long term that the seemingly endless winter will in fact come to an end, there are still some ominous weather systems on the way.

Next week could bring yet another round of the dreaded polar vortex, as the jet stream once again dips as far south as Virginia, The Weather Channel reports.

The following week may not be any better, the National Weather Service predicts, with an 8-to-14 day outlook that suggests large swaths of the country, from the Atlantic corridor to the High Plains, can expect temperatures as much as 50 percent below normal.

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