2026 Dorney Lake Marathon - Sep 26

2026 Dorney Lake Marathon - Sep 26 Countdown

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Race Information

Race2026 Dorney Lake Marathon - Sep 26
CityDorney
Date2026-09-26 at 09:10
Time Limit4 hours
Cutoff pace5:41/km
TimezoneEurope/London
Official SiteRunThrough
RegistrationRegister · 40 GBP

Race Day Weather

Average Temperature13.7°C / 57°F
Humidity82%
Wind23.8 km/h
Rain Chance39%
Typical ConditionsCool, calm late-September morning by the rowing lake at Dorney, near Windsor. Expect around 13-15C (55-59F) at the 09:10 start, climbing into the high teens by late morning, with moderate humidity and usually light wind across the open water. Early autumn here is often crisp and still - good marathon weather.

What to Prepare: Dress for a low-double-digit Celsius start that warms up, and pack arm sleeves or a throwaway top you can shed after a few laps. The course is fully exposed beside the lake, so a light breeze can feel cool early and there is no shade later - a cap and sunglasses help on a bright day. Road shoes are ideal on the flat paved surface.

Based on historical averages for race week. Use our Weather Score Calculator and What to Wear Guide for personalized advice.

Wind Impact on Race Day

Wind at 23.8 km/h can affect your marathon pace by 5-15 seconds per kilometer. Headwinds slow you down exponentially — a 20 km/h wind costs more than twice a 10 km/h wind.

Calculate your wind-adjusted pace →

Race-Week Climate

Based on 20 years of race-week weather (2005-2024), MERRA-2 reanalysis

Cooler Typical Warmer
Temperature 10.5°C 13.7°C 16.8°C
Dew point 6.8°C 10.5°C 13.9°C
Wet-day chance: 39% Runnability: 71/100

Data: NASA POWER (MERRA-2 reanalysis), NASA Langley Research Center

Course Profile

Course TypeFlat multi-lap road loop around Dorney Lake (Eton College rowing lake)
Elevation Gain54m
TerrainRoad
ProfileGenuinely flat and fast. The marathon runs repeated laps of the purpose-built Olympic rowing lake on a paved, traffic-free surface with only about 54m of total ascent across the whole race - essentially pancake-flat, which is exactly why runners come here chasing personal bests and qualifying times.
Boston QualifierYes — Check your BQ time

Prepare for 2026 Dorney Lake Marathon - Sep 26

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Featured In

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Frequently Asked Questions

What is the Dorney Lake Marathon route?

The Dorney Lake Marathon runs repeated flat laps around Dorney Lake, the purpose-built rowing lake near Windsor that hosted the London 2012 Olympic rowing events. The course is a paved, fully traffic-free loop tracking up and down the lake on smooth tarmac, with a turnaround on each lap. Because it is closed parkland with no road crossings, you get an uninterrupted, chip-timed run on one of the flattest surfaces in UK racing. Plan your splits with our pace calculator.

Is the Dorney Lake Marathon flat? Is it good for a PB?

Yes - it is genuinely flat and fast, with only about 54m of total elevation gain across the entire marathon. There are no hills, no road traffic and no technical sections, just smooth tarmac beside the lake. That is exactly why the venue has a reputation as a PB and qualifying-time course; the organisers have cited survey figures showing the large majority of marathon finishers achieving a personal best. Check what time is realistic for you with our race time predictor.

Is the Dorney Lake Marathon a Boston Qualifier?

Yes. The Dorney Lake Marathon is run on a UK Athletics-certified, accurately measured course (the route was measured by London Marathon course measurer Hugh Jones), so a finish here is valid for Boston qualifying (BQ) and a London Good For Age (GFA) entry. As one of the flattest certified marathons within reach of London, it is a popular choice for runners specifically targeting a qualifying time. Confirm the standard you need with our Good For Age tool.

What is the cut-off time for the Dorney Lake Marathon?

The current organiser, RunThrough, applies a strict 4-hour cut-off for the marathon distance - tighter than most UK marathons, so it suits runners confident of finishing comfortably under four hours (roughly 5:41 per km / 9:09 per mile). If you are closer to that limit, pace conservatively from the first lap; the time limit has varied between operators in past years, so always confirm the cut-off on your entry confirmation before race day.

How do I enter the Dorney Lake Marathon 2026?

Entry is open to the public online via the official RunThrough event page for the 26 September 2026 Dorney date, with no ballot. The marathon entry fee is around 40 GBP, and the same day also offers a half marathon, 10K and 5K. Capacity is limited and Dorney dates are popular, so enter early rather than relying on race-week availability.

What time does the Dorney Lake Marathon start?

All distances - including the marathon - start at 09:10 on Saturday 26 September 2026 from the event village at Dorney Lake. Aid stations on the lapped course mean you pass the same drinks point several times per lap, which makes fuelling and split-checking easy. Use our finish time calculator to set a goal pace before the gun.

How do I get to Dorney Lake?

Dorney Lake sits near the village of Dorney in Buckinghamshire, just outside Windsor and Eton, around 25 miles west of central London. Most runners drive - there is on-site parking - while those using public transport take a train to Windsor and Eton Riverside or Slough and continue by taxi, as the lake itself has no station. Allow extra time on race morning, as access roads into the rowing centre are narrow.

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