You want it to be just south for the heavy rains. But not too far south. That cooler air provides a dome for the warmer and more humid air to ride up and over.
@dendrite BHO is using the instrumentation at the top of the hill correct? I see Blue Hill COOP in the Nowdata. I ask because I see 96 and 95 there for the last two days. Scratching my head a bit at those values, but I suppose it could be right.
Logan won’t be due to so many sea breezes. Look at ORH, Blue Hill, and BDL. Maybe PVD too although I think they may be running cool still? Throw in CON and MHT too. I think many are close to top 5. It was a warm one.