Trail Running

The Fireflies of Josas

Trail Running covering 8 km to 12 km with up to 220 m D+ in Jouy-en-Josas (Île-de-France, France)

LocationJouy-en-Josas, Île-de-France, FranceShow on map(48.7645° N, 2.1690° E)
Date & StatusDecember 12, 2026Date confirmed
Elevation gainUp to +220 m

The Fireflies of Josas is an endurance sporting event in Jouy-en-Josas, Île-de-France, FR focused on Trail Running. Key features include Night Run, City Run, Festive, Nature & Off-Road.

The race program comprises 2 competitions, including Trail 12 km (12 km, +220 m D+), and Trail 8 km (8 km, +149 m D+). The next edition is officially confirmed for December 12, 2026. Official race regulations, course details, and registration information are provided on the organizer's website (traildujosas.com).

Official website
The Fireflies of Josas in Jouy-en-Josas (Work: "Malta - Sliema - Tigné Point - outer trail 05 ies", Photo: Frank Vincentz, License: CC BY-SA 3.0, Source: Wikimedia Commons)
"Malta - Sliema - Tigné Point - outer trail 05 ies" · Photo: Frank Vincentz · Wikimedia CommonsCC BY-SA 3.0
Cropped to 16:9 (960 × 540 px), WebP · Shared under the same license

Event characteristics

Night RunCity RunFestiveNature & Off-RoadIslandCostume Run

Races & distances (2)

CompetitionDisciplineDistanceElevation gainAltitude rangeCourse typeCourse & profile
Trail 12 kmTrail Running12 km+220 m89 m - 186 mLoop courseRoute & profile
Trail 8 kmTrail Running8 km+149 m89 m - 183 mLoop courseRoute & profile
Course & Elevation Telemetry

Course route & map

Distance
12 km
Elevation gain
+220 m D+
Elevation loss
-220 m D-
Altitude range
89 m - 186 m
Gradient (Avg / Max)
3.7 % / 23.1 %
Course format
Loop course
12 km+220 m D+
Start (S)Finish (F)
N246810FS48.7656° N, 2.1676° E

Elevation profile & course telemetry

Altitude from 89 m to 186 m above sea level (+220 m D+, -220 m D-)

Peak: 186 m·at 4.9 km·Ø 3.7 %
89 m121 m154 m186 m0 km2.4 km4.8 km7.2 km9.6 km12 km186 m
Event Information & Answers

Frequently asked questions (FAQ)

When and where does The Fireflies of Josas take place?

The Fireflies of Josas takes place in Jouy-en-Josas, Île-de-France, FR (start area at coordinates 48.7645° N, 2.169° E). The next edition is officially confirmed for December 12, 2026.

What races and distances are offered at The Fireflies of Josas?

The race program comprises 2 competitions, including Trail 12 km (12 km, +220 m D+), and Trail 8 km (8 km, +149 m D+). The competitions belong to Trail Running.

What is the course layout and elevation profile for The Fireflies of Josas?

The main competition (Trail 12 km over 12 km) is designed as a loop course featuring +220 m of elevation gain and -220 m of elevation loss, ranging between 89 m and 186 m above sea level. An interactive course map with a verified 3D GPS track, kilometer markers, and GPX download is available in the course section on this page.

Where can I find registration and official race rules for The Fireflies of Josas?

Official race regulations, course details, and registration information are provided on the organizer's website (traildujosas.com).