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A statistical analysis is made of the variation characteristics of fog events over the eastern Qinghai Province by means of the surface observation data from six stations over the region from 1977 to 2006. The results indicate that foggy days in the region had an uneven spatial distribution, with the high center at Menyuan (8.3 days per year, with the maximum up to 13 days per year); there were obvious annual, seasonal and daily variations in foggy days, and the number of foggy days per year decreased obviously; foggy days occurred mostly from 02:00 to 08:00, April to October, with the highest occurrence frequency in NNE or NE winds and the least in ESE and SSW winds (less than 1.5%); meanwhile, there was the highest occurrence frequency while air temperature being -1 ℃ to 5 ℃, and the relatively high occurrence frequency at higher humidity (over 88%) at various stations, except at Xining with the threshold humidity being 57%.