Final Boston Marathon Weather Forecast: It should be a great day to run fast

We are less than 48 hours from the 2026 Boston Marathon and it appears the weather conditions will be good for running fast. Since we initially published our first look at the weather two days ago, the forecast has only improved.

Initially, it looked like the weather for the elite pros would feature a temperature of 39 degrees Fahrenheit at the start and 43 at the finish and the wind was expected to be 9-10 miles out of the NW, gusting to 22 mph. Since then, the forecast has improved as the temperature is expected to be 4 degrees warmer, 43 at the start and 47 at the finish. That’s basically PERFECT for a marathon in terms of optimizing performance. Additionally, the direction of the wind has improved as well as it’s now expected it will have more of a westerly component to it as it’s now expected to come out of the WNW instead of the NW and will be 8 mph with gusts up to 18. That direction change will make it more of a tailwind than a cross wind.

The ideal wind for Boston would be WSW wind as the course runs largely west to east but there is a northerly component to it as shown by the following course map.

Overall, it’s going to be a great weather day for the runners looking to run fast. No, the wind isn’t perfect like it was in 2011 (close to 20 mph out of WSW) but if you are running Boston on Monday and don’t run the time you want, you won’t be able to blame the weather. According to LetsRun.com’s coaching/wind guru John Kellogg, the wind will probably be the equivalent of a 4-5 mph direct tailwind (with the gusting equivalent up to 11 mph) which should help take off at least one minute of time for the pros.

For spectators, it will be a little chillier than ideal.

Predicted Starting Conditions in Hopkinton 

Apple Weather screenshot

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Predicted Conditions Halfway in Wellesley

Predicted conditions at finish at Copley Square

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Talk about the Boston weather forecast on the world-famous letsrun.com message board/fan forum: Official 2026 Boston Marathon weather forecast discussion thread.

Did you know we often are right on the money with our Boston weather analysis? In 2011, we told you to watch out for potentially spectacular times and that is exactly what happened:  Official John Kellogg Is a Genius Thread (He Predicted The 2:03 on Boston)/

2011: Once In A (Marathon) Lifetime Conditions Forecast For Boston On Monday
2011: JK Babbles About The 2011 Boston Marathon