Jiayuguan has a very dry climate. It has four special characteristics. The first is lots of direct sunshine. The second is little rainfall. The annual average rainfall here is only 100 mm. The third is the climate's four distinct seasons. Winter and summer have huge temperature differences . Lastly, sand storms can be a problem in the Jiayuguan , with the wind sometimes reaching speeds of 3m/s . The best time to visit Jiayuguan and the ancient Silk Road is from May to October.