Yes, it is happening, in stages. Instead of re-explaining it, read the post by Matt Noyes which some bloggers have linked in recent updates.
For the more immediate future… Low pressure is tracking north northeastward, west of New England, sending a band of moderate to heavy rain into an unseasonably warm and humid late November air mass as the final day of the month begins. Dry air behind a cold front will put an end to the rain by dawn in most of eastern MA. It will not turn that cool behind the initial front. A secondary front or trough will pass by tonight from the west, with some clouds, and introduce slightly colder air for the first few days of December. This will be reinforced by another cold front passing by on Friday evening. This front will have little weather with it, just a few clouds.
We do warm up by Sunday and Monday ahead of the next storm system, but this time not to the levels we just saw. Another shot of chilly air arrives toward the middle of next week and this one may contain some snowflakes, though no big storm is seen at this time.
Boston Area Forecast…
OVERNIGHT: Showers, with an area of moderate to heavy rain and possible thunder moving through from west to east especially between 1:30AM & dawn. Mild and humid. Low 55-60. Wind S 10-15 MPH gusting to 20 MPH.
WEDNESDAY: Clouds and showers may linger at the coast and over eastern Essex County early in the morning otherwise sun becoming dominant with just some passing clouds. Temperature holding 55-60 much of the day. Wind SW 10-20 MPH gusting to 30 MPH.
WEDNESDAY NIGHT: Variably cloudy early, then clearing. Low 30-35. Wind W 10-20 MPH.
THURSDAY: Mostly sunny. High 42-47. Wind W 10-15 MPH.
FRIDAY: Mostly sunny. Low 26. High 48.
SATURDAY: Mostly sunny. Low 26. High 42.
SUNDAY: Partly sunny. Low 33. High 55.
MONDAY: Chance of rain showers. Low 39. High 51.
TUESDAY: Chance of rain or snow showers. Low 35. High 42.