Charles River Marathon Invitational
Race Day Weather
Comfortable temps, rain likely
Starting at 64°F, heat will be a factor from the gun — go out conservative and stay on top of hydration. Light winds shouldn't be a major factor for pacing. Rain is likely — waterproof your phone and bib, and consider a disposable poncho for the corral. High humidity (89%) will make it harder to cool down through sweat — increase fluid intake accordingly.
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Race Info
The Charles River Marathon Invitational is an invitation-only marathon in Boston, run on the same USATF-certified, ten-lap Charles River loop as the Charles River Marathon. Entry requires having finished a certified marathon since January 2024 within 20 minutes of a Boston qualifying time, with a limited number of fundraiser entries available. First run in September 2025, it drew a 73% Boston-qualifying rate among finishers. The race benefits the RACE Cancer Foundation's cancer research fundraising.