Another MA person here running the 10k

I haven't done the race weekend yet, but I have been following along with race threads on this board for the last few years, and I've coincidentally been there a few times. The temps can vary greatly. There have been cool years and warm years, dry weather and rainy. This year the half marathon was cancelled due to thunder storms that morning, and the marathon the next day was very cold.
That said, if you run outside in MA through the fall I think you'll be well prepared. You know how it is here, 70 degrees one day, 20 the next. It could be that way race weekend too. I have done the Princess weekend in February 3 times, and to prepare I run mostly outside which is cold, but inside on a treadmill once a week, because my gym is pretty warm. Makes me feel ready either way, and that has helped. I had 2014 where it was very warm and humid and 2015 where for the 5k it was literally freezing and then warmed a bit each day for the 10k and half, but was still cooler than 2014. 2016 was between the two extremes.