2026 Shonan International Marathon - Dec 6

2026 Shonan International Marathon - Dec 6 Countdown

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Race Information

Race2026 Shonan International Marathon - Dec 6
CityOiso
Date2026-12-06 at 09:00
Field Size~19,500 runners
Time Limit6 hours 30 min
Cutoff pace9:15/km
TimezoneAsia/Tokyo
Official SiteShonan International Marathon Organizing Committee (湘南国際マラソン大会組織委員会)

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Race Day Weather

Average Temperature6.7°C / 44°F
Humidity79%
Wind17.5 km/h
Rain Chance25%
Typical ConditionsCool, dry early-December weather on the Sagami Bay coast, usually around 8-14C at the 9:00 AM start with low rainfall and a steady sea breeze off the Pacific.

What to Prepare: Early December here is crisp and usually dry, but the open coastal road catches an onshore wind, so add a throwaway top layer and arm sleeves for the exposed bypass sections and the long Enoshima turnaround.

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 17.5 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 3.4°C 6.6°C 10°C
Dew point -1°C 2.8°C 7.4°C
Wet-day chance: 25% Runnability: 71/100

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

Course Profile

Course TypeOut-and-back coastal road marathon
Elevation Gain50m
TerrainRoad
ProfileFamously flat: an out-and-back along the Shonan shoreline and the West Shonan Bypass with only gentle road camber and a couple of bridge-ramp rises, which is why it draws PR-seekers.

Prepare for 2026 Shonan International Marathon - Dec 6

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Frequently Asked Questions

When and where is the Shonan International Marathon 2026?

The 21st Shonan International Marathon is held on Sunday, December 6, 2026, with a 9:00 AM gun start. It is an out-and-back course that starts and finishes around the Oiso Prince Hotel and the West Shonan Bypass in Kanagawa Prefecture, running along the Shonan shoreline between Oiso, Hiratsuka, Chigasaki and the Enoshima turnaround.

How do I enter the Shonan Marathon, and is there a lottery?

There is no lottery: full-marathon entry is first-come, first-served, and with roughly 19,500 spots it can sell out well before the deadline, so register early. The window opens in spring through the official site, RUNNET and LAWSON DO! SPORTS, and the standard full-marathon fee is 16,500 yen (a higher overseas-resident rate also applies). Set a realistic goal first with our race time predictor.

Is the Shonan Marathon course flat and good for a PR?

Yes. The route runs out and back along the flat Shonan coast and the West Shonan Bypass, with almost no climbing aside from a few short bridge ramps, which makes it one of the better near-Tokyo races for chasing a personal best. The catch is wind: the exposed seafront can throw a headwind one way, so pace conservatively with our pace calculator and save effort for the return.

Can I see Mt. Fuji on the course?

On a clear day, yes. As you reach the Enoshima turnaround and look back west along the coast, Mt. Fuji often rises over the bay, with Enoshima island in the foreground. December mornings on this coast are frequently clear and dry, which is part of the draw, but haze or cloud can hide the mountain on any given day.

What is the time limit, and is the course certified?

The time limit is 6 hours 30 minutes, comfortable for most runners but not as forgiving as some 7-hour Japanese races, so build a buffer on the flat early miles. Note that the current course is not a JAAF-certified (日本陸連公認) layout — certification was discontinued from the 2015 edition, when a partial road-profile change took effect — so finishing times are not valid for record or Boston-qualifying purposes.

What is the My Bottle Marathon concept?

Shonan rebranded as the My Bottle Marathon, an environmental initiative to eliminate single-use cups and plastic bottles on course. For the full marathon, carrying a personal bottle is a mandatory participation condition — every runner must start with a bottle holding at least 200 ml of fluid and refill at the on-course points rather than grab disposable cups (the 10 km Fun Run requires a personal cup instead). It is one of the first large marathons to push for near-zero plastic waste on the route, so plan to bring a soft flask or handheld for race day.

Do I need a visa to run as a foreign visitor?

Many nationalities (US, UK, EU, Australia and others) can enter Japan visa-free for short tourist stays; confirm your own passport's requirement before booking, and note that an overseas-resident entry fee applies. The Shonan coast is easy to reach from Tokyo, roughly an hour by train to the Oiso and Hiratsuka area, making a race-weekend trip from the capital straightforward.

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