Looks like MHT has 30 year normals, but I’m not sure what the statistical process is to incorporate (or not incorporate) that chunk of years from the 90s.
Not sure what they’re using for normals at MHT because the climate records didn’t start back up there again until ASOS took over in 96 or 97 there. So they would technically be outside the 1991-2020 window.
Maybe they’re using 15 year normals there while everyone else is on 30?
+4 for a day isn’t really a big deal. But +4 for a month is pretty torchy. But really it comes down to standard deviations and the +1.5 or +2 SD numbers aren’t exactly at our fingertips.