Boston Marathon 2026 Weather: What 10 Years of Data Tell Us

The 130th Boston Marathon takes place on Monday, April 20, 2026 — Patriots’ Day in Massachusetts. Roughly 30,000 runners will line up in Hopkinton for the 42.195 km journey to Boylston Street, and every one of them will be at the mercy of a single variable no training plan can override: weather.

Boston is uniquely exposed to weather disruption. Its point-to-point course runs west to east, placing runners in the path of prevailing westerly winds for over two hours. The mid-April date sits in a meteorological no-man’s-land between late winter cold snaps and early spring warmth. The result is a race where conditions swing dramatically from year to year — and sometimes within a single race.

To help you prepare, we analyzed 10 years of race-day weather data for Boston (2016–2025), pulling hourly observations from the National Weather Service station at Boston Logan (KBOS) and inland stations near the start in Hopkinton. Here is what the data tells us — and how you can use it to build a smarter race-day plan. For a full interactive breakdown, see the Boston Marathon race page on Havik.

10-Year Weather Summary (2016–2025)

Across the ten-year window, Boston Marathon race-day weather exhibits more variance than any other World Marathon Major. Here are the headline numbers:

• Temperature: Mean race-day temperature of 12.7 °C (55 °F), with an observed range of 3 °C to 21 °C — an 18-degree spread.
• Wind: Average sustained wind of 15–20 km/h, predominantly from the west and southwest. Headwind exposure on the course is common, particularly between Wellesley (km 21) and Boston College (km 33).
• Precipitation: Measurable rainfall on 3 of 9 race days (excluding the cancelled 2020 edition), giving an approximate 30% rain probability.
• Humidity: Typically 50–70% relative humidity at gun time, rising through the morning in warmer years.

“Boston’s weather is more variable than any other major marathon. The difference between a PR day and a survival day can come down to which April week the calendar lands on.”

Year-by-Year Race-Day Conditions

The table below summarizes observed conditions at gun time for each edition. Temperature is the mean between start and finish; wind is sustained average at course level.

The data makes one thing clear: there is no “typical” Boston weather. The standard deviation in race-day temperature is 4.7 °C, nearly double that of the Berlin or Chicago marathons. Planning for a single scenario is planning to be surprised.

How Weather Affects Your Boston Pace

The Newton Hills and Headwind Exposure

The Boston course drops roughly 140 m from Hopkinton to the finish, but the famous Newton Hills (miles 16–21 / km 26–34) inject four significant climbs totaling about 90 m of elevation gain at the worst possible time — when glycogen stores are depleted and fatigue is accumulating. These hills face west, funneling prevailing headwinds directly into runners already battling uphill grade. The combination of grade-adjusted effort and aerodynamic drag can elevate perceived exertion by 15–20% compared to flat, sheltered segments.

Temperature Impact

Research published in Medicine & Science in Sports & Exercise and confirmed by race-day performance data shows a clear thermal penalty for distance runners:

• Optimal range: 7–15 °C (45–59 °F) — minimal thermoregulatory cost.
• Every 5 °C above 15 °C adds approximately 1.5–2.5% to finish time for mid-pack runners. For a 3:30 marathoner, that translates to 3–5 minutes per 5 °C of excess heat.
• Below 5 °C, muscular efficiency drops and the risk of hypothermia rises, particularly if rain or high wind is present (as in 2018).

Wind Impact

Boston’s point-to-point layout means you cannot “get the wind back” on a return leg. A sustained 20 km/h headwind adds roughly 6–10 seconds per kilometer at marathon effort, depending on runner mass and frontal area. Over 42.195 km, that compounds to 4–7 extra minutes — enough to miss a BQ by a wide margin. Drafting behind a group of similar-paced runners can reduce aerodynamic drag by up to 40%.

Run your numbers through Havik’s Boston analysis tool to see weather-adjusted split predictions for your goal pace.

What to Wear for Boston 2026

Based on the 10-year median temperature of ~13 °C (55 °F), here is a starting-point gear plan:

• Top: Singlet or lightweight short-sleeve. Arm sleeves are a versatile add — easy to push down or remove as you warm up.
• Bottom: Half-tights or split shorts. Avoid full tights unless the forecast is below 7 °C.
• Gloves: Light gloves for the corral and first 10 km — cheap enough to discard at an aid station.
• Rain layer: A disposable poncho for the Athletes’ Village wait. If rain is forecasted during the race, consider a lightweight, breathable shell you can tie around your waist.
• Hat: A light cap shields against both sun and rain, and retains heat in cold conditions.

Remember: the 10-year range is 3 °C to 21 °C. Prepare for the median, but pack for the extremes. Check Havik’s forecast starting two weeks before race day for personalized clothing recommendations based on actual conditions.

Pacing Strategy for Boston 2026

Boston’s course profile punishes aggressive early pacing more harshly than any other major marathon. The first 16 miles are a net downhill of roughly 120 m, which makes target pace feel deceptively easy. Runners who bank time in the first half pay compound interest on the Newton Hills.

Key Pacing Principles

• Miles 1–5 (km 1–8): Run 5–10 seconds per mile slower than goal pace. The net downhill and adrenaline will mask the true cost. Discipline here pays off after mile 20.
• Miles 6–16 (km 9–26): Settle into goal pace. This is the most sheltered section with gentle grades. Take advantage of the terrain.
• Miles 16–21 (km 26–34) — Newton Hills: Accept 10–20 seconds per mile of slowdown on the climbs. Maintain effort, not pace. Heartbreak Hill (mile 20.5) is not the steepest climb, but it arrives on fatigued legs.
• Miles 21–26.2 (km 34–42.2): The final 5 km are downhill into the city. Runners who paced conservatively can accelerate here while those who went out fast fade into the wall.

Weather compounds these dynamics. A headwind on the Newton Hills increases the effort cost of each climb. Heat in the first half accelerates dehydration, which accelerates the fade. Cold rain saps body heat, making late-race muscle cramps more likely.

Havik generates weather-adjusted pace splits for Boston based on your goal time and the current forecast. The model accounts for temperature, wind direction relative to each course segment, humidity, and elevation — producing per-kilometer targets tuned to conditions.

The Bottom Line: Prepare for Anything

Ten years of data confirm what Boston veterans already know: April in New England is a coin flip. Most years land in the 8–17 °C range with moderate wind — solid racing weather. But at least once per decade you get a 2018-style outlier that tests survival, not fitness.

The best strategy is not to hope for perfect weather. It is to build a plan that adapts to whatever the atmosphere delivers. That means having a warm-weather plan, a cold-weather plan, and a rain plan before you arrive in Boston — and making your final call on race morning.

Havik exists to make that decision easier. Our analysis engine combines real-time forecast data, course-specific wind modeling, and physiological pace adjustments to give you a race-day blueprint tailored to conditions — not averages.