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Furbutt After Dark 12-Hour Ultra

location_on

calendar_today 23 May, 2026 – 24 May, 2026

directions_run Running

language Official Website

sell $15.00

About the Event

New this year: We are increasing the registration fee to $15 to help cover expenses for the race. Since we are charging a fee this year, note that you will not be expected to bring any food or beverages to share. We will be providing food, water / ice, and Gatorade at the start / finish area. Please bring any additional food or beverages that you anticipate needing during the race for your personal use.

The backyard format is based on Lazarus Lake’s Backyard runs. Runners have one hour to complete the 4.167-mile course. Runners must be in the corral at the top of the next hour ready to start the next loop, or they’re out.

In addition to being a challenging run, Furbutt's After Dark 12-hour Backyard is also a great way to experience the backyard format. This is an excellent opportunity to run your first marathon, 50K or 50-mile distance because the backyard format forces you to rest early and often, which can help you run a longer distance than you thought possible. Please note that to participate in this event, you will need to follow backyard rules: 

Lap Distance: Each lap is 4.167 miles (6.706 kilometers). A completed lap is denoted as 1 Yard. This distance ensures that running 12 laps in 12 hours equals 50 miles.

Time Limit per Lap: Runners must complete each lap within one hour. Any remaining time within the hour can be used to rest, eat, hydrate, or prepare for the next yard.

Start of Each Lap: Yards begin every hour on the hour. Runners who fail to start at the exact time are eliminated.

No Pacing or Assistance on Course: Runners must complete laps without personal aid (one common aid station will be at start / finish area).
Crew support will only be allowed between laps at the start/finish area.

Course Rules: Runners are responsible for monitoring their hydration and should carry a handheld or hydration vest as appropriate for weather conditions. Runners must wear a reflective/light vest and carry a light or headlamp after dark. 

Elimination: Failing to finish a lap within the hour results in elimination OR runners who quit voluntarily or miss the start of a lap are also eliminated.

Winner: The last runner standing must complete their final lap solo to be declared the winner and in this race, there may be multiple runners who run all 12 yards. All others technically receive a DNF ("Did Not Finish") designation.

Safety: Runners are responsible for monitoring their physical condition, hydration level, and fueling. Organizers may intervene if a runner is deemed unfit to continue.

 

Note: This event is inspired by Lazarus Lake, for more information on backyard ultras check out his website https://backyardultra.com/. 

Races Offered

Furbutt After Dark 12-hour

May 23, 2026

straighten

Distance — 50 Miles

terrain

Type — Running

timer

20:00

sell

$15.00

Weather History

These values represent the 3-year monthly averages for May in Lorton.

thermostat Temperature
13.5° / 23.1°
wb_sunny Feels like
12.1° / 22.0°
light_mode Avg sunshine hours
9h 48m
water_drop Avg rainfall
4.1 mm
ac_unit Avg snowfall
air Avg wind speed
9.6 km/h (Light breeze)
opacity Sweat loss rate
Moderate
terrain Course conditions
Firm and slightly soft
sunny Max UV Index
High (6.0)
humidity_mid Humidity
72.4%
wb_twilight Sunrise
05:56
nightlight Sunset
20:14

About Lorton

Learn more about the host city, Lorton.

Scenic view of

Lorton is a community in Fairfax County, Virginia. This article also covers the nearby areas of Fort Belvoir and Mason Neck.

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Hotels & Places to Stay

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