Boston Marathon 2027 weather: what race day will likely feel like

The 131st Boston Marathon is on Monday 19 April 2027, Patriots' Day: 42.2 km point to point, from Main Street in Hopkinton through Ashland, Framingham, Natick, Wellesley, Newton and Brookline to the finish on Boylston Street in Boston. Here's what race day has usually felt like, town by town, for a runner in the middle of the field.

What will the weather be like at the 2027 Boston Marathon?

Usually cool and breezy, with dry air: good running weather on about half the days, and a cold, wet or warm one now and then. In the records, a Wave 3 runner started at about 11° and finished at about 12°, with a dew point near 2°. RunFast's engine rated race day Good on 5 days in 10, Fair on 3 and Tough on 2.

The heat stress (WBGT, the number race medical teams use) was usually about 14°. It reached Moderate or more on about 2 days in 10, and High on less than 1. The warmest race day in the records reached 30°.

Where does the weather usually cost runners time?

Mostly the wind, sometimes the heat. On the middle day of the records, the weather cost a 5:30-per-km runner about 2 minutes over the whole race, and 13 minutes or more on 1 day in 10. The wind was the main cause on about 5 of those days in 10.

Start · HopkintonFraminghamWellesleyHeartbreak HillFinish · Boylston Street123456Historic

Most of the course is green on a middle day: the weather costs less than 1% there. Scattered stretches turn amber, a little slower, by about 1 to 1.5%, and the one run that stands out is the finish, from Kenmore Square to Boylston Street, where the turns put the wind in runners' faces about as often as behind them. The breeze is usually from the west at 13 to 16 km/h, and as the course runs east almost all the way, it was more often a tailwind than a headwind, on about 4 days in 10 against about 3, though it changes from day to day.

What is each section likely to feel like?

Each section with its usual race morning, hour by hour, timed for a Wave 3 start at 10:28 and a steady 5:30 per km.

1. Hopkinton and Ashland

From the start on Main Street in Hopkinton, past the Stylianos Kyriakides "Spirit of the Marathon" statue at mile 1, then east on Route 135 through Ashland. The first miles drop steadily downhill. It's about 12° on the long downhill start, after a wait at about 7° in Athletes' Village, and the westerly, about 13 km/h, was more often behind runners than against them.

2. Framingham and Natick

Past the historic Framingham train depot at mile 6.5, then West Central Street through Natick. About 13° through Framingham and Natick, with the wind mostly behind on about 4 days in 10. The heat stress is usually Low, and Moderate or more on about 2 days in 10.

3. Wellesley

Through Wellesley, past halfway, to where Route 135 joins Route 16 on Washington Street. About 13° past halfway, with the heat stress usually Low, and Moderate or more on about 2 days in 10.

4. Newton: the fire station turn and the hills

Route 16 drops through Newton Lower Falls, then the course turns right at the fire station onto Commonwealth Avenue, after mile 17, and climbs the Newton hills: past the Johnny Kelley "Young at Heart" statue at mile 19.2 to the crest of Heartbreak Hill at mile 20.8. The wind, about 14 km/h from the west, was more often behind runners on the hills, on about 4 days in 10, than against them, on about 3. This section was rated Good on 5 days in 10, Fair on 3 and Tough on 2.

5. Brookline: Cleveland Circle and Beacon Street

Bearing right at the reservoir onto Chestnut Hill Avenue to Cleveland Circle, then left onto Beacon Street, mostly downhill through Brookline. About 14°, the warmest part of the course, with the westerly at about 14 km/h more often behind than against on the run down Beacon Street.

6. Kenmore Square to Boylston Street

Past the Citgo sign in Kenmore Square and the "1 mile to go" mark at mile 25.2, under Massachusetts Avenue, right onto Hereford Street and left onto Boylston Street to the finish near the Boston Public Library in Copley Square. It's about 12° at the finish, and the wind, about 16 km/h from the south-west, was mostly in runners' faces on about 4 days in 10, about as often as it was behind them.

What should runners wear and pack for race day?

Old layers for Athletes' Village, race kit for about 12–14°, and something for the wind. The B.A.A.'s information for athletes has the start schedule, the bus loading times and the Athletes' Village rules. From the weather records:

• Throwaway layers for Hopkinton. It was about 7° during the wait, 2° or colder on 1 morning in 10. Clothes left in Hopkinton are donated, and only the B.A.A.'s clear start-area bag is allowed on the buses.
• Race kit for 12–14°. That's shorts and a light top for most runners, with gloves and arm sleeves for a cold, wet morning.
• A cap or a light shell on wet days. Rain fell during the run on about 2 days in 10.
• Sunscreen on clear days. Heat stress reached Moderate on about 2 days in 10.

US clocks went forward on 14 March 2027, so every start time is Eastern Daylight Time. Official timing ends at 5:30 pm, about six hours after the last starter crosses the line.

When does the real forecast open?

Ten days before the race, in the RunFast app: on 9 April. Load the course with your own pace and wave, and RunFast shows the heat and the wind at each stretch as you get there. From then on, trust the forecast over this preview.

How did we work this out?

The course was run again on every day from a week before to a week after 19 April, in each year from 2015 to 2024: 150 days. Each run started at Wave 3's 10:28 (the 2026 time), Eastern Daylight Time, at a steady 5:30 per km, on that day's hourly Copernicus ERA5 weather, with its dew point and sunshine. RunFast's engine, the same one the app uses, worked out the heat stress and the weather's toll, and rated the run and each section. The start-area wait is the lowest temperature between 7:00 and the start, and a wet day has 1 mm of rain or more.

ERA5's grid cells are about 25 km across, so a few of them cover this course, from rural Hopkinton to the city. Streets, trees, shelter and the city's own warmth don't show. The course line follows the streets on the B.A.A.'s 2026 course map, so it's close to the course but not the organiser's own file; the B.A.A. hasn't published a 2027 map yet. Historic weather, not a forecast.

Sources: The Boston Athletic Association's Boston Marathon page, with the 2027 date; its information for athletes, with the 2026 start schedule; the 2026 course map; and the 2027 rules and policies; ERA5 hourly time series (Hersbach et al., 2020). Course line drawn from © OpenStreetMap contributors. Contains modified Copernicus Climate Change Service information (2026). Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.