The Autumnal Equinox is the astronomical start to the fall season, which officially begins at 9:54PM tonight.
Right on cue, temperatures will be plummeting overnight as a dome of high pressure takes over.
This high keeps us partly to mostly clear and temperatures will slip into the 40s early Sunday morning especially along and north of the Mass Pike, including the Merrimack Valley and the Worcester Hills. Southwestern NH could see pockets of 30s, which has prompted a Frost Advisory to be issued from midnight to 9AM Sunday.
As far as our Saturday goes, it will be breezy at times with temperatures into the upper 60s to low 70s through the afternoon under some filtered sunshine as the wind shifts to out out of the northwest.
Sunday, after a chilly start, temperatures will rebound back into the mid to upper 60s under mostly sunny skies, so for those participating in the 30th Annual Boston Marathon Jimmy Fund Walk from Hopkinton to Boston, be sure to wear the layers. Temperatures will likely start in the mid 50s at the starting line.
Chilly night and mild days are in the forecast for the start of the work week, as well. With high pressure still in control, sweater weather will be here on Monday with highs struggling to make it out of the 50s under mostly sunny skies.
Tuesday, we start off dry before a system to our west slides in, ushering a slight warm-up and shower threat Tuesday afternoon and evening. Showers with embedded thunderstorms remain in the forecast for the middle of the week.
Even though the forecast remains wet for Wednesday, it will likely be the warmest out of the next 7-days with highs into the upper 70s.