As you were heading out to campus this morning, you may have wondered why we’ve traded this weekend’s sunny skies and warm temperatures for today’s cool and cloudy weather. These unseasonably chilly conditions are thanks to what meteorologists call a “back door” cold front. Typically, cold fronts in the U.S. approach from the west or northwest. In the Northeast during springtime, however, it’s fairly common for cold fronts to approach from the north or northeast on the backside of a high pressure situated to our north. Winds behind such a cold front are from the east or northeast, allowing cool maritime air to filter in and replace warmer continental air. This is precisely the setup for last night and early this morning, which is why temperatures will top out at a mere 56°F (13°C) this afternoon.
Looking forward, Boston will see a rebound to seasonable temperatures tomorrow as the high pressure currently over Maine moves offshore, allowing the return of southeasterly winds. Temperatures for the rest of the week will remain warm, with highs Thursday and Friday in the mid- to low 70s°F (low 20s°C). The chances of showers and even a thunderstorm increase through week’s end, thanks to both sustained southerly winds ushering in moisture-rich air and a cold front approaching Friday night into Saturday morning.