After a cool and damp day today, big changes are on the way.
A weak area of low pressure pulls away overnight, and skies start to clear out. A warm front moves across the region on Friday, allowing warmer air to start to move in. A shower or thunderstorm is possible during the evening, then very warm to hot and increasingly humid air settles in for the weekend as high pressure builds in. Away from the coastline, temperatures should get well into the 90s both Saturday and Sunday. Sunday looks like the hottest day, with some upper 90s possible across the Merrimack Valley and Southern New Hampshire. A cold front will approach late Sunday, with some showers and thunderstorms likely at night. Monday will be more seasonable, but there may still be plenty of clouds, with some showers, mainly in the morning.

Thursday night: Gradual clearing, with some patchy fog, especially near the coast. Low 45-52.
Friday: A mix of sun and clouds, chance for a late-day shower or thunderstorm. High 74-81, cooler along the coast.
Friday night: An evening shower or thunderstorm, otherwise partly to mostly cloudy with some patchy fog near the coast. Low 53-60.
Saturday: Sunny, hot, and becoming humid. High 90-97, cooler along the coast.
Saturday night: Clear to partly cloudy. Low 64-71.
Sunday: Sunny and hot, clouds start to move in during the afternoon with showers and thunderstorms possible late in the day. High 91-98, cooler along the coast.
Sunday night: Cloudy with showers and thunderstorms likely. Low 60-67.
Monday: Mostly cloudy, some showers possible in the morning. High 71-78.