Annecy sits at around 450 metres above sea level, but the trails that surround it climb well above 1,700 metres. That range in altitude means conditions vary significantly across the season, and picking the right window makes a real difference to your experience.

The main season: May to October

The bulk of the trail network is rideable from May through to October. By early May, snow has cleared from most mid-altitude trails and the ground has dried out enough to ride comfortably. July and August are the busiest months, with good weather and long daylight hours, though summer heat can make long climbs harder work. Temperatures in the valley regularly reach 30°C, so early morning starts are worth considering.

September is widely regarded as the best month by local riders. Temperatures drop to more comfortable levels for climbing, the crowds thin out, the forest colours start to change, and trail conditions are typically at their best after a summer of use and the first autumn rains.

October is still viable, particularly for lower and mid-altitude trails. Higher routes on Semnoz can become wet and slippery earlier in the month if rain sets in.

Semnoz specifically

Semnoz tops out at 1,704 metres, and its upper trails are often snow-covered until late May or even early June depending on the year. The descent from the summit is the main draw for many visitors, so it is worth checking current conditions before heading up. Local riders and the MTB Annecy Facebook group are a reliable source for real-time updates.

Spring: possible but variable

March and April see the trails starting to open up at lower altitudes around Veyrier and Talloires. The lakeside trails and forest tracks in these areas dry out faster than the higher ground. However, Semnoz and other higher routes often remain closed or muddy well into the spring. If you’re visiting in the spring, plan for lower trails and treat anything higher as a bonus if conditions allow.

Winter

The trail network is not designed for winter riding. Semnoz operates as a small ski area from around December to March, and most trails at altitude are either under snow or too muddy. Some riders use road bikes or gravel bikes around the lake during winter, but for MTB purposes the season is essentially over by November.

Monthly Overview

Period	Conditions
April	Lower trails can be rideable when dry, higher trails inaccessible
May	Lower trails opening, higher trails still unreliable
June	Most trails open, good conditions building
July–August	Peak season, hot, busy, good trail conditions
September	Best overall: cool, quiet, excellent conditions
October	Still rideable, watch for early rain at altitude
November–March	Off-season, most MTB trails closed or inaccessible

One thing to keep in mind

Conditions vary year to year. A dry spring can open the trails two or three weeks ahead of schedule, while a late snowfall can push things back. The best approach is to check recent reports before you travel rather than relying on fixed dates.