Cool temperatures at sunrise will climb to the upper 40s by the time the race starts in Hopkinton at 10 a.m. It should be in the mid- to high 50s when the field is crossing the Back Bay finish line in the afternoon.
That’s considered perfect weather by long-distance runners.
Temperatures climbed to a high of 89 degrees last year, when race organizers offered an unprecedented deferment to runners who opted to sit it out. About 2,300 people took them up on it and will run this year instead.
They’ll be part of the field of 27,000 heading to the starting line on Monday morning for the 117th edition of the race.