Heat advisories are posted for much of Southern New England Thursday afternoon as temperatures will reach the 90s. You might be asking yourself, when will the fall air finally arrive? If you don’t like the heat, the good news is that Thursday is the final day of extreme heat in this current go-around, and perhaps for the entire season, as the first really big push of fall-like air arrives late Thursday night and into the weekend.
While thoughts may turn to flannel shirts and hot apple cider, don’t get too used to the coolness, and certainly don’t put away the summer wear.
Cooler weather arrives in waves, not in one major season-ending transition. In the fall, we often see a couple of days of cool weather followed by a return to warmth and, in years like this one, high humidity as well. In every year, eventually the outbreaks of cooler air last a little bit longer and the transition back to the warmer weather becomes less frequent and less intense. The odds of seeing high temperatures at or above 90 start rapidly diminishing after the middle of September, but they don’t completely fall away until early October. This is the type of year where we actually might see 90-degree weather as late as Columbus Day.
Average high temperatures have continued to fall for the past several weeks and we’re now in the mid-70s. Averages, of course, include extremes, and all of us here in New England know that the weather is actually rarely average. This summer, we’ve been on the warm side of average and on the extreme side of that.
This year, the Bermuda high — a large area of high atmospheric pressure — has been firmly entrenched and keeps providing us with unseasonable humid and unseasonably warm weather. This is going to be the dominant player in our upcoming weather pattern next week, so fall hasn’t fully arrived yet. In fact, the summer pattern looks to be quite strong, and we should consider this weekend’s cool weather just a temporary interruption.
Monday will become a transition day between the cool air and the humid air. By Tuesday, I expect dew points to once again be well into the 60s and even lower 70s, and it looks to me like humidity will continue the rest of next week and perhaps into the following weekend. This fact will play into the forecast of Hurricane Florence as well.
A continuous flow of air from Canada would keep it cool and feeling like fall for more than just a few days. It would also shunt Hurricane Florence out to sea and make the likelihood of that storm affecting New England slim to none. However, because the Bermuda high is the dominant player, that hurricane is going to be steered in a westward direction. The precise configuration of that high-pressure system is what will determine where Florence will go next week.
It’s way too early to say whether Hurricane Florence will affect us, but I recommend using the cool and comfortable air this weekend to at least think about hurricane preparedness, as next weekend probably wouldn’t leave you enough time.
Follow Dave Epstein on Twitter@growingwisdom.