Boston Marathon forecast

The Boston Marathon’s early outlook has shifted toward a cooler, drier race day on Monday, April 20. (bostonglobe.com) The Boston Globe reported on April 13 that forecasts were running 5 to 15 degrees below Boston’s mid-April norm, after earlier race-week projections looked less settled. Boston’s average temperature through the first 10 days of April was 46.3 degrees, according to National Weather Service climate data. (bostonglobe.com) (weather.gov) The race’s first official starts are scheduled from 9:00 a.m. through 11:21 a.m., with para athletics and mobility divisions leaving first and the sixth open wave leaving last. The Boston Athletic Association’s 2026 wave schedule lists Wave 1 at 10:00 a.m., Wave 2 at 10:15 a.m., Wave 3 at 10:28 a.m., Wave 4 at 10:41 a.m., Wave 5 at 11:01 a.m., and Wave 6 at 11:21 a.m. (boston.com) (baa.org) That timing matters because runners will be on the course for hours, from a morning start in Hopkinton to afternoon finishes in Boston. Boston.com reported that athletes are expected to finish throughout the day, not in a single weather window. (boston.com) The race is the 130th Boston Marathon, set for Patriots’ Day, Monday, April 20, 2026. The Boston Athletic Association said 30,000 participants from more than 130 countries and all 50 states are expected for this year’s field. (baa.org) (boston.com) Boston weather in April can swing sharply, and marathon history in the city includes heat, rain, wind, and even snow. WCVB said its race page would keep updating conditions as April 20 gets closer, underscoring how much can still change in the final week. (wcvb.com) For now, the clearest takeaway is timing: the forecast is pointing cooler than normal, and the first runners will be on the road at 9:00 a.m. on April 20. (bostonglobe.com) (boston.com)