With a heat index pushing toward 100 degrees this week, the cities of Bangor and Portland have set up a cooling stations to help residents find relief.

The National Weather Service issued a heat advisory across most of Maine for Monday and Tuesday because of the extreme heat and humidity affecting much of the area between Bangor and Millinocket. Overnight temperatures will also remain high and not offer much relief.

For those without air conditioning, Bangor has set up a cooling station at the city’s Park and Recreation building at 647 Main St. until 9 p.m. Monday and from 8 a.m. to 9 p.m. Tuesday. Officials urge residents to use this room for a respite from the hot weather.

In Portland, the East End Community School cafeteria was opened to the public as a cooling station Monday and will be again Tuesday from 10 a.m. to 4:30 p.m. The city notes the Portland Public Library, across from Monument Square, is also available for people seeking to cool off between 10 a.m. and 7 p.m.

Monday night’s low temperature will only dip to about 71 degrees, and Tuesday’s temperatures are again expected into the 90s before expected thunderstorms bring relief late Tuesday night or early Wednesday morning.

Meanwhile, the Maine Department of Environmental Protection has issued an air quality alert about unhealthy high ground-level ozone levels. On Tuesday, high ozone levels that began building in the New York City area are expected to blow up the coast to Maine.

“The combination of heat, humidity and poor quality will exacerbate the effects of each,” according to a DEP press release.

In a press release, Bangor officials offered tips to keep cool and safe during the hot spell:

— Drink plenty of water to stay hydrated

— Stay in air conditioned spaces

— Check in with any elderly family or neighbors

— Pets need to stay hydrated, too

— Dress appropriately (wear light-colored, loose fitting clothes)

— Wear sunscreen

— Postpone unnecessary outdoor activities (if possible)

The DEP, which publishes updated ozone forecasts on its website, also advised residents to avoid strenuous outdoor activities during the afternoon.

Follow the Bangor Daily News on Facebook for the latest Maine news.