What can be expect in term of weather in late march for rainbow mount

Well, the temperature may range from 45 F to 70 F during that period of time. Although there may have many sunny days, the temperature difference will still be large in day and night. So you are suggested to prepare jackets, thin sweaters, long sleeves and jeans.

Thanks for the prompt reply..
How do i go about travelling from xian to zhangye.. prefer by rail..

You can take the direct train from Xian Railway Station. The schedules are 03:00, 03:49, 04:00, 05:05, 05:34, 06:57, 07:38, 09:52, 10:30, 10:41, 11:01, 11:09, 19:33, 21:13, 22:00 and 23:30. The ticket fare of soft sleeper is CNY415.5 and hard sleeper is CNY272.5. You can search for more details on this website.