Weather in Tibet around Sept. 7-20

Hi,

I am going to Tibet around Sept. 7-20. According to LP, the lows in Lhasa would be in the 50's. however, I am not sure how cold it gets in the surrounding visiting sites. Anyone has any idea of what kind of weather I should prepare for during this time? Clothing suggestions? (I know a similiar post was posted on this but hasn't been answered so apologize for the duplicate post).

Thanks