I want to visit and maybe have a tour of the distillery at 蒙牛酒业工业园.

Well, you can try to contact the company to consult the visit. The email address is: naren2000777sohu.com
Also you can ask if there is a public shop.
As for the weather, it would be sunny or cloudy for most of the days. In early May (May. 1- 10), it would be still cold there, with the average temp of 45F. If you are going during this period, you should take warm clothes with you. If you are going later, the temp would be around 60F. It is much warmer.