Abstract
In order to find the changes in rainfall characteristics and to examine the affect on rice production under rainfed conditions, a statistical analysis was carried out for 50 years daily rainfall record at Vientiane Municipal, Laos Meteorological Observatory. The rainfall recode was divided into two periods for each 25 years. Although total annual rainfalls have no trend, annual maximum daily rainfalls fluctuate and increase at the same probability year. Frequency of drought is increasing in the second period and more severe drought on September is increasing. On the contrary, in the first period heavy rainfalls causing flood such as over 100 mm/day are distributed intensively on August and September, although in the second period such rainfalls are also found from May to July.
