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Halloween should be dry but chilly in Philly, and a region-wide freeze is likely Thursday morning

Readings are forecast to drop into the 20s in parts of the region Thursday morning.

Sam Nicotera, 15, works with other West Philly neighbors to decorate their homes near 51st and Catharine Street last. He may need a sweater Tuesday night.
Sam Nicotera, 15, works with other West Philly neighbors to decorate their homes near 51st and Catharine Street last. He may need a sweater Tuesday night.Read moreTom Gralish / Staff Photographer
    by Anthony R. Wood
    Updated 
    Published 

Rain is expected to hold off until late Tuesday night, but the candy-seeking brigades are going to be treated to a December-ish chill, forecasters say, and it appears that the 2023 “growing season” is about to come to an official end throughout the region.

Temperatures during the witching hours Tuesday will be in the upper 40s to around 50 degrees; however, the winds won’t be strong enough to blow off any headpieces.

Wednesday readings will struggle to get out of the 40s on what is looking like the last day of the growing season for “pretty much everyone,” said Michael Silva, a lead meteorologist at the National Weather Service Office in Mount Holly.

» READ MORE: The winter outlooks are going for a mild start, and it's due to warm up after this cool shot

By weather service definition, growing season ends in a given county when the temperatures reach freezing or lower in the majority of the county. That’s been slow to happen this year as the growing season has continued throughout the Mount Holly coverage area, including the Poconos, said Silva’s colleague Eric Hoeflich.

Those growing seasons, which begin with the last 32-degree reading of spring, have been lengthening in recent decades, tracking with the worldwide warming trend.

The lows on Thursday morning are due to tumble into the 20s in parts of Bucks, Chester, and Montgomery Counties.

» READ MORE: PHL is often freeze-resistant. This was a classic instance.

The weather service forecast low for the official station at Philadelphia International Airport is 33 degrees, but areas elsewhere in the city are expected to reach freezing.

The airport station is often a holdout, being near a swamp and the Delaware River.

In 147 years of recordkeeping, the official median first-freeze date in Philadelphia is Nov. 8. In 38 of those years — or about 25% — it has occurred in October. But that’s happened only once in the 21st century, on Oct. 31, 2011.

And the chill won’t last. “After this cold shot,” said Silva, “it looks like we turn milder.”