The 130th Boston Marathon is set for Monday, April 20, and the forecast is trending toward a cool, dry race day after a frontal system brings scattered showers through the Boston region on Sunday. Those showers are expected to end before sunrise Monday, leaving cooler air in place for runners and spectators along the 26.2-mile course.
Race-morning temperatures are expected to start in the low 40s, with afternoon highs reaching the mid- to upper 40s. Any north or northwesterly flow should stay under 10 mph as the system moves away, a setup that would be a relief after recent years when heat has been a much bigger story. The average daily high over the past 10 Boston Marathons has been 61 degrees, but marathon-day highs topped 70 in 2017, 2020, 2021 and last year, when the race reached 73 degrees. By contrast, the coldest marathon day since 2000 came in 2018, when the high hit 43 degrees.
That history matters because weather can shape how the race unfolds, especially in the later miles. Four of the last 10 Boston Marathons saw rain, and the 2023 race was the last run in wet conditions, making this year’s setup look calmer by comparison. Ken Mahan said he was starting to feel a little optimistic about the outlook and told runners and sidewalk spectators they should feel the same about race day. The forecast also lines up with cooler, dry air expected to settle over Eastern Massachusetts by early Monday, running about 5 to 15 degrees below average for this time of year.
The biggest question now is not whether the Boston Marathon will have weather, but whether the chill will be enough to help runners without making the early miles uncomfortable. A mild, steady race day has not been the recent norm in Boston, and that is exactly why this forecast stands out.
