One school district canceled classes for Monday. Two other school districts and a regional high school are instituting an early dismissal.

As temperatures threaten to hit 100 degrees Monday, Lowell Public Schools said enough was enough and called a heat day. The school's website said there will be no school "due to the forecasted extreme heat conditions. Weather.com says it will get as high as 96 degrees Monday, and forecasters are warning of even higher heat indices.

Another nor'easter? No, just a really hot day.

Also in the Merrimack Valley, where a heat advisory has been issued, Haverhill and Lawrence Public Schools, along with Whitter Regional Tech in Haverhill, will call an early dismissal.

Holoyoke Public Schools also has an early dismissal.