Temperatures are due to fall into the 30s on Thursday morning in the Philadelphia region, and stiff northwest breezes roughing up the newly born leaves could drive wind chills into the 20s.

Unfair? Maybe. Cool and unusual on the precipice of May? Definitely. The forecast temperature ranges for Thursday — lows in the upper 30s, highs in the mid-50s — would be normal for mid-November. But it’s not all bad.

Readings could be tantalizingly close to the Philly record of 34 on Thursday, and a freeze warning is posted for western Chester County, where temperatures could drop to 32 or slightly below, said Sarah Johnson, a lead meteorologist at the National Weather Service Office in Mount Holly.

However, she said, the air is going to be too arid for any frost, and her colleague Alex Staarmann said that any frost or freeze in the immediate Philadelphia area is all but out of the question.

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“It looks like it’s going to be too breezy and dry,” he said. In fact, it is so breezy and dry that the weather service has issued a “fire watch” for the entire region until 10 p.m. Wednesday, and from 9 a.m. to 10 p.m. Thursday.

The winds Wednesday night and Thursday morning, 15 mph with gusts to 25, will be too strong for frost to settle on plants or other surfaces. Barring a killer freeze such as we experienced last month, blossoms and blooms should be OK with the cooldown: Ever wonder why flower shops tend to be chilly?

Friday morning’s lows will be similar, and though the winds will back off some, they’ll still be in the 10-mph range and the humidity low.

The chill also might give pollen sufferers a break, said Donald Dvorin, an allergist who is a National Allergy Bureau pollen counter, at a time when counts are spiking, especially for the oaks, which explains that green veneer on the car hoods. Tree pollen jumped to “extreme” levels on Wednesday, he reported, seven times higher than they were last Friday.

“If it’s under 40 degrees the pollen is not released as readily,” said Dvorin, who is with the Allergy and Asthma Doctors practice in Mount Laurel.

“The trees actually shut down. They know to close with lower temperatures.”

The weekend should be more favorable for tree reproduction and various human outdoor pursuits, if not for pollen sufferers.

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Temperatures are to crest past 60 Friday, reach the mid-60s on Saturday, and 70 on Sunday, with no rain.

Staarmann said it’s possible that after Friday we will be done with the 30s until the fall.

“Hopefully it will be the last surge of really cool air we get for the season,” Staarmann said. “It’s just kind of winter’s last gasp.”