2026 Shimada Oigawa Marathon - Oct 25

2026 Shimada Oigawa Marathon - Oct 25 Countdown

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Race Information

Race2026 Shimada Oigawa Marathon - Oct 25
CityShimada
Date2026-10-25 at 09:00
Field Size~6,000 runners
Time Limit7 hours
Cutoff pace9:57/km
TimezoneAsia/Tokyo
Official SiteShimada Oigawa Marathon in Liberty Organizing Committee (しまだ大井川マラソンinリバティ実行委員会)

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Race Day Weather

Average Temperature14°C / 57°F
Humidity81%
Wind16.1 km/h
Rain Chance32%
Typical ConditionsMild, mostly dry late-October weather in Shizuoka, typically around 14-20C at the 9:00 AM start, with low humidity and only a small chance of light rain.

What to Prepare: Late-October running in Shizuoka is close to ideal: a singlet or short-sleeve top with a light throwaway layer for the start is usually enough, and the riverbank can be breezy, so a cap helps on the exposed sections.

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 16.1 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 11°C 13.9°C 16.4°C
Dew point 7°C 10.3°C 14.5°C
Wet-day chance: 32% Runnability: 74/100

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

Course Profile

Course TypeRiverside out-and-back on a dedicated path
Elevation Gain40m
TerrainPaved riverside path
ProfileOne of Japan's flattest marathons, run almost entirely on the 'Liberty' riverbank cycle path beside the Oi River; the only real undulation is the short rise onto the embankment near the Kawagoe ruins and the descent back down.
Boston QualifierYes — Check your BQ time

Prepare for 2026 Shimada Oigawa Marathon - Oct 25

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Frequently Asked Questions

When and where is the Shimada Oigawa Marathon 2026?

The 18th Shimada Oigawa Marathon in Liberty is held on Sunday, October 25, 2026, with a 9:00 AM full-marathon start. It takes place in Shimada City, Shizuoka Prefecture, on the 'Liberty' course beside the Oi River — said to be the first marathon course in Japan purpose-built on a riverbank.

How do I enter, and is there a lottery?

There is no lottery: full-marathon entry is first-come, first-served and closes the moment the 6,000-runner cap is reached, so popular slots can sell out well before the deadline. Registration runs through the official site and major Japanese entry platforms such as RUNNET, and the standard full-marathon fee is 10,000 yen. Set a realistic goal first with our race time predictor.

How flat is the course, and is it good for a PB?

It is one of the flattest road marathons in Japan. The route runs almost the entire distance on the dedicated 'Liberty' riverbank path; the only meaningful climbs are the short rise up onto the Oi River embankment near the Kawagoe historic site and the descent back down. With even ground and no real hills, it is a popular personal-best and marathon-debut race. Plan your splits with our pace calculator.

What is the time limit, and are there mid-course gates?

The full marathon has a generous 7-hour time limit and, unusually, no intermediate cutoff gates along the course — you only need to finish within seven hours. That combination makes it one of the most beginner-friendly and forgiving marathons in Japan for a first 42.195 km.

Is the Shimada Oigawa Marathon a Boston-qualifying race?

Yes. The full-marathon course is certified by the Japan Association of Athletics Federations (JAAF / 日本陸連公認), so an official chip time can be used toward a Boston Marathon qualifier if you meet your age-group standard. Check where you stand with our Boston qualifying calculator.

How do overseas runners get to Shimada?

Shimada sits in central Shizuoka, roughly midway between Tokyo and Nagoya. The nearest Tokaido Shinkansen stop is Kakegawa, with a short local connection to Shimada Station, putting the race within reach of a Tokyo race-weekend trip. Many nationalities can enter Japan visa-free for short tourist stays, and no ESTA or eTA is currently required — confirm your own nationality's rules before booking.

What is the weather usually like in late October?

Late October in Shizuoka is typically mild and dry, often 14-20C at the start with comfortable humidity and only a small chance of light rain. It is good racing weather, though the open riverbank can catch a breeze, so a cap and a throwaway start-line layer are worth packing.

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