Guilin weather in January is the coolest with an average temperature of 7~9C, but it is warmer camparing to Beijing Weather(https://www.travelchinaguide.com/climate/beijing.htm) and Shanghai Weather(https://www.travelchinaguide.com/climate/shanghai.htm) . You need to wear warm winter clothes as well. You may have little chance to see snow there. Anyhow, focus on the weather forecast of Guilin before you go there.