The Xi'an International Horticultural Exposition was held in the ecological zone of Chanba from April 28,2011 to October 22. The regional meteorological observation data from the year of 1959 up to the present were used to analyse the climatic background and highly affecting the weather from April to October. The results show that. (1) From 50 s to 60 s.high temperature days were more than those from 70 s to 80 s.but in 90 s they were getting more again. The Exposition park was 0. 2 ? higher than downtown. The forecast service should focus on the high temperature from June to August. (2) The heavy rain and strong convective would occur in July which was the most important prevention time. (3) From late March to late July,the thunderstorm had a rising trend;in late July to early September it would decline. July and August were the main period for prevention of thunderstorms. (4) The windy weather appeared from march to August. Attention should be paid to it (5) More than 70% of rainy days happened in July to October. The time from September 23 to October 3 was the high-risk period of heavy rains which might cause floods.%西安世界园艺博览会于2011年4月28日～10月22日在西安浐灞生态区举办,会期覆盖整个汛期,高影响天气多发,可能对世园运行及游客参观带来不利影响.通过利用1959～2009年西安气象观测资料及近年西安区域站资料,对4～10月的气候背景及高影响天气进行了统计分析,结果表明:(1)20世纪50～60年代高温日较多,70～80年代有所下降,90年代后又呈上升趋势,园区气温较市区偏高0.2℃,6～8月是高温预报服务重点；(2)7月为西安暴雨高发期,园区易发生短时强降水,是暴雨及强对流重点关注和预防时段；(3)3月下旬～7月下旬雷暴日呈上升趋势,7月下旬到9月上旬呈下降趋势,9月中旬略有上升,之后平稳下降,7月、8月是雷暴影响主要时段；(4)西安市区大风天气3～8月出现天数较多,4～8月为6、7级风高发期,应给予重点关注;(5)70％以上的连阴雨主要发生在7～10月,7月、9月为连阴雨高发期,9月23日～10月3日为高发时段,应重点关注连阴雨及期间的暴雨造成的洪涝灾害.
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