Waves of warm air to roll across northeastern US through late April

Bursts of warm air, interspersed between brief cool shots, will surge into the northeastern United States through the end of the month.

“We expect alternating waves of warmth and chill to continue to the Northeast, and to some extent in the Midwest, through April and into early May,” AccuWeather Lead Long-Range Meteorologist Paul Pastelok said.

Periods of unseasonable warmth will be occasionally slashed by pushes of cooler air that drop temperatures closer to or slightly below normal.

Waves of warmth/chill

On average, the warmer days will outweigh the cooler days helped in part by the increasing angle of the sun and length of daylight.

In the short term, the next wave of warmth will arrive this weekend following the return of more seasonable conditions through Friday.

“A warmup will ensue in time for Easter weekend,” AccuWeather Meteorologist Ryan Adamson said.

Temperatures in the upper 60s and 70s F will return to much of the mid-Atlantic by Saturday. Highs in the lower 60s will be felt as far north as Maine.

Highs will soar back into the 80s from Washington, D.C., to Baltimore, Philadelphia and Newark, New Jersey, on Easter Sunday.

An uptick in humidity will accompany the warmer air.

The transition between the warm and cool waves will typically be marked by showers and thunderstorms, some of which could turn locally damaging to end the holiday weekend.

“A cold front moving in from the west will bring the risk of showers and thunderstorms by Sunday afternoon,” Adamson said. “A few storms may contain gusty winds and small hail.”

Adams expects cooler, drier air to be ushered in for the start of the new week with temperatures returning back to near normal.

A surge of unseasonable warmth will likely return again around the middle of next week, followed by another cooldown.

Those hoping to get an early start on their garden should beware of the potential for freezing temperatures at night during the cool spells over the next several weeks.

Average last frost

“There is still a high risk of frost and freeze events from northwestern Virginia through upstate New York and northern New England into the first week of May,” Pastelok said.

“The risk in this area diminishes, but is not zero during mid-May,” he added.

Those who do take advantage of the warm days by getting a jump-start on their gardens should be prepared to protect sensitive plants and vegetables in case of a frost or freeze.

“The threat of frosts and freezes is over for the season from Tennessee to the Carolinas and southeastern Virginia,” Pastelok said.

On average, the last frost usually occurs by May 1 along the I-95 corridor from Washington, D.C., to Boston, and by May 15 across the central and southern Appalachians, New York and much of New England.