Last Gasp?
Amazingly, Boston hasn't seen a 90 degree temp this month...that is likely to change this week as the heat and to some extent the humidity make a return. A frontal boundary has been draped to our south for the last couple of days...the result has been varying amounts of high clouds limiting the sun at times. That boundary is in the process of washing out and shifting east. As it departs, it will allow for heat to build in and replace it. High temps over the next three days will flirt with 90 and there is an outside chance that a few communities actually see an official heat wave. While this heat will make it a bit uncomfortable the humidity levels won't be off the charts and somewhat manageable.
The warm pattern will hold through Thursday but by the end of the day clouds will be advancing in and showers will follow shortly after. The cold front responsible for the showers will be working through the Northeast and like so many Summertime cold fronts will be very slow to get through and lingering clouds and perhaps showers will hang around Friday morning too. After that cooler and less humid air slides in for the upcoming weekend...sweet!