the temperature during winter (December to February) falls to under zero degree Celsius, and many trees in the town are covered in ice. If you are a lucky person, you will see snow in December. Therefore, the time is considered as the best time to visit Sapa. Furthermore, spending about 3-4 days in Sapa, if you have time to stay in there longer. In Sapa, you can enjoy Love market or traditional market as well as homestay at H'mong people to learn more about lifestyle and culture of them. You can read more about tips or travel guide at http://www.sapatrekkinghomestay.com