Marathon weather looks cool

Marathon Monday in Boston is shaping up cooler than normal, with early forecasts pointing to dry air and temperatures that favor runners more than spectators. (bostonglobe.com) The 130th Boston Marathon is scheduled for Monday, April 20, 2026, on Patriots’ Day, with the first athletes starting in the morning and all runners expected to cross the line before 11:30 a.m. under the event’s new six-wave format. (baa.org) The Boston Athletic Association said the field size remains 30,000 runners, but this year’s six waves will range from about 3,200 to 7,100 athletes instead of the four roughly 7,500-runner waves used in recent years. (baa.org) For marathoners, cooler weather usually reduces overheating risk over 26.2 miles, and Boston’s course has a long record of race-day weather shaping outcomes as much as tactics. (wgbh.org) Boston’s weather history cuts both ways. In 2011, temperatures near 46 degrees at the start and a strong tailwind helped Geoffrey Mutai run 2:03:02, which still stands as the course record. (wgbh.org) A year later, the race started in the 60s and climbed into the mid- to upper-80s, prompting organizers to urge runners to slow down or defer as medical tents filled with heat-related cases. (wgbh.org) Cold can be punishing too. The 2018 race brought temperatures in the 30s and 40s, plus rain and a stiff headwind, turning the day into one of the most difficult editions in recent memory. (wgbh.org) This year’s outlook follows a warmer stretch in New England, with regional forecasters saying a cooldown is expected by race weekend and into Monday. (wmur.com) If that cooler pattern holds through April 20, Boston runners could get the kind of manageable conditions that are rare enough on this course to become part of the story by themselves. (bostonglobe.com)