Many parts of Maine were blasted with frigid air Thursday night into Friday morning, and meteorologists say the overnight cold temperatures broke decades-old records.

Portland reported a low of 2 degrees, and Augusta reported a low of 3 as of 7 a.m. Friday, according to the National Weather Service.

Gusty winds made those single-digit temperatures feel even colder, with overnight wind chills falling as low as minus 8 degrees at Portland International Jetport and minus 9 at Augusta State Airport.

Forecasters had warned Thursday that overnight wind chills in parts of Maine could fall as low as minus 30 degrees, prompting many communities to open warming shelters.

Portland’s previous record low this time of year was 7 degrees, set in both 1945 and 1989, meteorologist Jerry Combs said.

In Augusta, the record low was set in 1991 at 4 degrees.

A scientist with the National Oceanic and Atmospheric Administration said Friday that two large-scale atmospheric events could be contributing to the cold.

First, a disruption in the polar vortex is helping build atmospheric pressure over the Arctic and Greenland, said Amy Butler, a research scientist in NOAA’s Chemical Sciences Laboratory. That pressure “acts like a boulder” in the polar jet stream, pushing arctic air to lower latitudes, she said in an email.

A polar vortex disruption — which scientists call a sudden stratospheric warming — is rare so early, Butler said. Such events have only happened by this point of the season a couple of times since 1958.

Another potential factor Butler pointed to is a high-pressure system building over the Pacific Ocean near Alaska.

That system is blocking air from flowing across the continental U.S., resulting in the West Coast staying warmer than usual while the East remains colder than typical for “at least the next two weeks,” Butler said.