From 80s to 30s: Forecasters say fall will finally arrive in the Lehigh Valley this week

BETHLEHEM, Pa. — Consider this your cozy sweater alert.

Days of temperatures in the mid- to lower 80s will be wiped out by a cold front later this week, forecasters say, ending a bonus stretch of warmth and finally ushering in classic fall weather.

Temperatures in the Lehigh Valley are expected to hit 82 degrees Monday and drop to 37 degrees by early Thursday morning.

According to the Washington Post, the cause of the summer-like temperatures is a phenomenon that has unfolded thousands of miles away.

There's an expansive and record-breaking marine heat wave in the North Pacific Ocean that has contributed to a surge in temperatures across the United States.

Beneficial rain, then the chill of fall ahead

After a dry start to the week, Tuesday night into Wednesday will feature a cold front approaching the region, the National Weather Service said in its latest forecast discussion.

Much-needed rain will arrive as well, with forecasts nearing an inch for the majority of the region.

“Some areas likely will fall short, while some overperform,” the weather service said, noting details will be ironed out as the cold front gets closer.

Almost the entirety of the Lehigh Valley has been classified as “abnormally dry” by the U.S. Drought Monitor, which has parts of the Mid Atlantic and Northeast in extreme drought status.

According to the Northeast Regional Climate Center, the Lehigh Valley is in a rainfall deficit of 5.50 inches over the past three months, and 7.41 inches over the past year — our 23rd warmest on record, while the past two years have been the 8th warmest on record.

Here comes the cold

Canadian high pressure will move in Wednesday night, the weather service said, remaining in control through the end of the week.

Seasonably cool temperatures are expected Thursday and Friday, with highs generally in the low to mid 60s.

Overnight lows Wednesday night are expected to range from the upper 30s to the upper 40s, with some mid 30s likely Thursday night in colder spots of the Lehigh Valley and the southern Poconos.

“This will be the result of mainly clear skies and light winds. Would not be surprised to see the first frost headlines of the season for northern New Jersey and southern Poconos by the end of the week,” the forecast discussion said.

The weekend forecast is less certain, with the possibility of a storm system tracking into the region that could bring a soaking rainfall on Sunday.