It is Ok to travel to Lijiang during Chinese New Year(https://www.travelchinaguide.com/essential/holidays/spring-festival.htm) . You can experience the happy atmosphere of traditional Chinese festival there. It will be cold during that time since the temperature may be low to 0C. You need to wear warm winter clothes.

Always sunny and blue sky in Lijiang during Chinese New Year,warm in daytime(15degree at noon),and cold at night(could be below -5C). The only problem of traveling to Lijiang during these days is too many tourists,and heavy traffic.