Abstract: Two years' rainfall record at Lhasa reveals wide fluctuation and the amount in 1936 is about eleven times the amount in 2935. In 1936 the amount of rainfall received in Nlay, June, July, August and September was 4986.8mm, more than 70% of this amount was contributed by the exceptionally strong southwest monsoon climbing over the lofty ranges of the Himalayas and the other 20% contributed by thunderstorms.