les40bosses.fr

Trail les 40 Bosses

Name: Trail les 40 Bosses
Start: 2025-12-06
End: 2025-12-07
Location: Saint-Leu-la-Forêt

location_city Saint-Leu-la-Forêt

flag France

calendar_today 06 Dec, 2025 – 07 Dec, 2025

directions_run Running

language Official Website

About the Event

Prepare for the ultimate trail challenge at the Trail les 40 Bosses this December 2025! As the toughest trail in Ile-de-France, it features the monstrous 120km "Le Monstre" (a UTMB 100M Qualifier), alongside other epic distances like 75km, 45km, and accessible 10km-20km options. With Decathlon Herblay as an official partner, enjoy exclusive benefits including bib collection and a 10% running gear discount. Whether you're an elite ultra-runner or a trail beginner, join this legendary event set in the beautiful Vexin French Regional Natural Park. Registrations and volunteer sign-ups are now open—be part of the adventure

Races Offered

120 km 5500m d+

Dec 06, 2025

straighten

Distance — 120K

terrain

Type — Trail running

timer

15:30

75 km d+ 3300m

Dec 06, 2025

straighten

Distance — 75K

terrain

Type — Trail running

timer

15:30

20 km nocturne d+900m

Dec 06, 2025

straighten

Distance — 20K

terrain

Type — Trail running

timer

18:30

45 km d+ 2100m

Dec 07, 2025

straighten

Distance — 45K

terrain

Type — Trail running

timer

08:00

20 km d+ 900m

Dec 07, 2025

straighten

Distance — 20K

terrain

Type — Trail running

timer

10:00

10 km d+ 400m

Dec 07, 2025

straighten

Distance — 10K

terrain

Type — Trail running

timer

14:00

Weather Overview

These values represent the 3-year monthly averages for December in Saint-Leu-la-Forêt.

Temp (°C)

Feels Like (°C)

thermostat 3.4° / 7.9°

wb_sunny -0.8° / 4.1°

Wind (km/h)

Humidity (%)

air 14.2 /

water_drop 87.5%

Temp (°C)

Feels Like (°C)

Wind (km/h)

Humidity (%)

thermostat 3.4° / 7.9°

wb_sunny -0.8° / 4.1°

air 14.2 km/h

water_drop 87.5%

About Saint-Leu-la-Forêt

Saint-Leu-la-Forêt is a commune in the Val-d'Oise department, in the northwestern outer suburbs of Paris, France. It is located 19.9 km (12.4 mi) from the centre of Paris. In 2021, it had a population of 15,979.