Yesterday's high temperature was a record-breaking 91 degrees, surpassing the previous record for Oct. 2 — 88 degrees — which stood since 1927.
Hitting 90 in October is such a rarity that it’s only occurred 10 times since 1914, which is as far back as Millersville University records go, university meteorologist Eric Horst said.
“Yes, it’s a rare event. No, it’s not unprecedented,” Horst said.
“Autumn is a transitional season, and you get warm spells and cool spells in September. Doing it in October is way more rare,” he said, noting today’s high temperature is expected to top out around 60.
“A 30-degree difference — that’s an impressive shift,” he said.
Today should also bring drizzle, clouds and gray skies.
A cold front moving in overnight was expected to bring the cooler temperatures and keep them here for a while, Horst said.
The recent unseasonably high temperatures were from a strong jet stream ridge that hung over the southeast since September, Horst said.
“The ridge kind of expanded northward Tuesday into the Ohio Valley and (Wednesday) into the North Atlantic,” he said. “That let the warm air flow up into here.”
That’s over now.
“The weekend into next week will be much more seasonable for what I consider normal in October,” Horst said.
That means sunny, pleasant days with highs in the upper 60s and nights in the upper 40s, he said.
Saturday morning, however, could see temperatures dip to the lower 40s, possibly the upper 30s — maybe even low enough for a rural farm valley in the county to see frost, he said.
But frost is more likely in the northern or central parts of Pennsylvania, he said.
Lancaster County shouldn’t expect frost until mid-month, according to Horst.