Altitude and mountain weather
Popular treks cross passes above 3,800m within a few days of leaving Bishkek at 800m. Ala-Kul in particular catches people out: a hard pass at altitude, often attempted without acclimatisation, with snow possible in any month.
Rescue capability is limited and slow. There is no equivalent of an alpine helicopter service in much of the country, so self-sufficiency, a satellite messenger and honest assessment of your own fitness matter more than they would in Europe.
Roads and shared transport
The Bishkek–Osh highway crosses two high passes and is the main artery of the country. Landslides, snow and heavy truck traffic make it genuinely dangerous, and marshrutka minibuses are driven fast.
Winter closes mountain roads for months. Check whether a route is open before committing to it, because the detours are enormous.