We only get to put one number for each morning and each afternoon in the 7 day forecast. We try to put a number that represents the average conditions or the conditions that most people will encounter. But in this case, that doesn’t really tell the whole story. The 7 day forecast should come with at least one big asterisk this week that reads "not available in all areas" and possibly a double asterisk that reads "heads-up…its sea breeze season."
Winds will be very light early Monday morning. With clear skies and light winds, temperatures tend to plummet. There will likely be a few spots, mainly low lying wind sheltered locations, that bottom out in the low 20s. Meanwhile Boston probably won’t drop much below 30. That explains the 28 on Monday morning.
Later on Monday, winds will increase from the southwest around 10 mph to near 20 mph with higher gusts. Southwesterly winds will pump in mild air by March standards and some areas will warm well into the 50s. There should be enough of a prevailing wind to prevent any sea breeze. However, water temps are only around 40. So, any location that is downwind of the water (south facing beaches like the South Coast, much of the Cape and the Islands) will stay in the low 40s. That explains the 51 on Monday afternoon.
Southwesterly winds will continue on Tuesday and the warm-up continues. Areas well inland will warm well into the 60s. However, winds will be much lighter on Tuesday, and that will likely allow a sea breeze to develop. As the land warms up, the warm air rises. We can’t have a vacuum. So, cool ocean air rushes in to replace the rising warm air. That cool air is the sea breeze and that will keep areas within a few miles of the water in the low 50s.
Winds from the southwest will pump even warmer air into Southern New England on Wednesday. Wind speeds should be somewhere in between…not as strong as Monday or as light as Tuesday. We should see several readings in the 70s on Wednesday. But, once again that will NOT include any south facing beach, much of the Cape, or the Islands where temps may not get out of the 50s. Its a little too soon to predict if a sea breeze will develop. If so, areas near the coast probably won’t warm above the 60s. If not, the 70s will be widespread. That should explain the 70 on average in the 7 day forecast for Wednesday.
A cold front arrives on Thursday bringing us a round of showers and, as you might expect, some cooler weather. Right now there is a lot of uncertainty surrounding when the front will arrive. If it gets here early on Thursday, we probably won’t see many readings above 50 Thursday afternoon. If the front doesn’t get here until late in the day, we should be able to squeeze out another day in at least the 60s almost everywhere. Either way, expect falling temps Thursday night.
Bottom-line enjoy the warm* weather while it lasts.
* Not available in all areas.
