Another day into the 90s for most of us – even for Boston – though, the heat wave for BOS was broken yesterday. For many of us though, including Bob in Millis (one of our weather spotters) today was the 8th straight day in the 90s. Tomorrow will not be #9! Not even close. In fact, it may even be a shock to the system.
We still have a chance of an isolated shower/storm through this evening, mainly in W & N Massachusetts into S. NH. I don’t anticipate anything “severe” out of these storms, though there is a cell rolling through the Seacoast of New Hampshire now that has a lot of lightning with it. Always remember, warned storm or not, “When thunder roars, go indoors.” I always say this to the kiddos when I do school visits – and while it sounds a little trite, it’s important. Lightning can travel some 10-15 miles from a storm (on average) and has even traveled some 20-30 from some storms. If you’re close enough to HEAR the thunder, you’re in danger of being hit by lightning. Again, any storms we see tonight will be isolated… the real “show” starts overnight and carries on into Friday.
Relief from the heat is on the way with highs tomorrow not expected to make it out of the 70s! We’re in the middle of a bit of a “squeeze play” between a front to our north, and a low to our SW. As the two come together, as they’re expected to tomorrow, it will give even more “lift” to the atmosphere… What does that mean exactly? Think of a really wet sponge or dishcloth: 
The BEST chance for heavy rainfall will be south of the Mass Pike. The NWS has issued a Flash Flood WATCH for late tonight into Friday evening. 
Remember, this is a WATCH which means “watch out, the potential is there!” A WARNING, on the other hand, would mean “It’s happening NOW.” So, with a WATCH issued for all day tomorrow, we’ll be “watching” for any “warnings” to be issued for specific areas that do get pummeled with rain. North of the Pike, the potential for drought relief is looking slim. Southern New Hampshire may miss out on this completely. Don’t worry too much though, because there are still some more scattered showers in the forecast for Sunday and Monday.
For the weekend, Saturday looks to be your better “outside” day. Highs will be in the mid 80s, but cooler along the coastline. Heading to Coldplay on Sunday? The forecast looks like it’s on the “Up & UP,” which may mean you’ll get to enjoy a “Sky Full of Stars.” It sounds like “Paradise.” Such a heavenly vieeeewwwwewwwwewwww. 
Enjoy. – Breezy