A heat advisory goes into effect for most of Massachusetts from 11 a.m. Thursday through 8 p.m. Friday. Boston officials are urging residents to stay cool and drink water as temps and humidity rise. Boston officials also want residents to recognize the signs of heat exhaustion. StormTeam 5 has Boston's only live radar scanning the skies over Massachusetts all day, every day. Friday brings similar conditions, and the advisory remains active until 8 p.m.High temps combined with moisture create dangerous conditions.