Historically, the Buddhist festival of Losar is celebrated around the time of the winter solstice, but Ladakh follows a different set of rules when it comes to them celebrating their Losar festival. There is an interesting story that is at the root of the Losar celebrations in Ladakh. King Jamyang Namgyal, on the eve of setting out on an expedition against the Balistan forces in winter was advised not to lead an expedition before the new year. To solve the problem, keeping the regard of the advice, he pre-poned the New Year celebrations in Ladakh by two months. This became established as a tradition and since then Losar is celebrated on the 1st day of the eleventh month every year (as per the Lunar calendar).
During this day, the entire Ladakh rejoices in festive colors. Dances are performed at Buddhist monasteries and people go in large numbers to these monasteries to offer their prayers. All the shops are shut and the people take to the streets decked with colorful prayer flags. The locals celebrate the day with special meat and the local beer Chang flows freely.
I was in Leh when the 2011 Ladakh celebrations were held at Leh. The previous day the entire Leh market was decorated with banners and prayer flags. On the day of Losar, all the locals turned up in their traditional clothing and boy did they turn in huge numbers. If I remember right, the entire Leh market road was filled with people. There was a stage in the middle of the market, where popular Bollywood and Ladakhi songs were played by a group of artists. It is certainly a lot of fun to be in Leh during a Losar festival.