Hiking boots are ok - I've seen people go up in sneakers. Lava's togh though and it's far mor comfortable if your boots are thick soled with solid caps. You'll need a permit for the last 150m above the cable-car.

Weather is always an issue at this height. With luck you won't have snow or ice but I've also seen Teide (from afar) under a thick snow and ice cover.



The picture was taken in February (!!) 2005. On La Palma, where I was staying at the time, Roque de los Muchachos (2436m) was covered with ice as well ...