Boston missed 80 on Saturday, but dew points climbed throughout the day. Sunday will be even more humid with dew points in the low 70s. With high dew points coupled with temperatures in the low to mid 80s, it will feel more like July than September.
A cold front will be moving through the region tomorrow. That cold front is triggering thunderstorms from Toronto down to Houston! Showers and thunderstorms will likely weaken tonight, but could re-fire Sunday. We're not expecting severe weather, but a few downpours are likely (late Sunday morning into the early afternoon). Rainfall amounts will likely stay below a half inch.
Once the cold from passes to the east, dew points will drop from the 70s into the 40s by Monday morning. It will feel like fall most of the week - highs in the 70s, lows in the 40s and 50s.