PORTLAND — The plunging temperature is playing a role in the closing of schools in Maine’s largest city.

Portland officials decided to close schools because of a temporary shortage of compressed natural gas used in half of the city’s 26 school buses. Some were low enough on fuel that there were concerns of kids being stranded in the cold weather.

The National Weather Service says the temperature plunged to minus 8 in Portland. It was even colder elsewhere, with readings of 11 below in Lewiston-Auburn, 21 below in Fryeburg and 38 below at Escort Station.

Temperatures will be warming through the week.

In Portland, a power surge that affected pumps at the city’s compressed natural gas station caused the temporary fuel shortage. School officials are making contingencies for Friday.

Schools in Lewiston and Auburn stayed open.