Andover and North Andover are bracing for mid-to-upper 90s this week, with a heat index up to 102 degrees and little overnight relief for anyone without air conditioning.

The National Weather Service's Heat Advisory runs Tuesday at 11 a.m. through Wednesday at 8 p.m., with a high near 96 on Wednesday and Tuesday night's low only dropping to around 80. Relief arrives Wednesday night, when temperatures fall to about 72, and by Saturday highs settle near a much more comfortable 82.

Elderly residents, young children, and anyone without AC face the greatest risk. Stay hydrated, limit outdoor activity during peak afternoon hours, and never leave kids or pets in a parked car.

Frye Pond Beach in North Andover was listed as closed as of early July due to bacteria tied to a Merrimack River wastewater overflow — the result of a broken 42-inch sewer main in Haverhill that's been discharging about 8 million gallons of untreated wastewater a day into the river. Haverhill's mayor says drinking water is unaffected, but residents should avoid contact with the river near and downstream of the break until repairs finish. Plum Island and Salisbury Beach have reopened, but 50 Massachusetts beaches remain closed statewide as of Monday, including spots in Beverly, Danvers, Lynn, Salem and Swampscott. Elevated bacteria can cause GI illness and flu-like symptoms.

Check current beach closures at the state's Interactive Beach Water Quality Dashboard on mass.gov. No cooling centers have been announced locally, but libraries and senior centers may offer air-conditioned space. In an emergency, call 911.