Based on NCEP 2.5o í 2.5o reanalysis data of 850 hPa wind、temper and the highest daily temperature data from 2001 to 2010, a result is found that the highest daily temperature changes have good consistency Through statistical analysis ,and have a obvious 6~28 days volatility in the spring. Southerly wind in shaanxi area on the 850 hPa when 6~28 days volatility in a positive phase,the temperature becomes higher than normal, anticyclone controls shaanxi area on the 850 hPa when 6~28 days volatility in the negative phase, the temperature is decreased obviously. According to the contrast, So define the influencing areas.After doing lag correlation analysis with 15 day LFO temper of the influencing areas and 6~28 day LFO temper of 850 hPa in whole field,a key areas is found,which are area 40o~45oE,65o~70oN. Further study 6~28 day LFO on the 850 hPa temper, 6~28 day LFO temper of the key areas would influence the influencing areas, Results also show that 6~28 day LFO temper of the key areas have a good relationship with the highest daily temperature of Shaanxi 15 days later. Prediction test shows that the 6~28 day LFO temper of 850 hPa in the key area can be good indicators of extended range forecast of spring in shaanxi.%利用2001—2010年陕西省89站日最高气温资料和NCEP/NCAR逐日850 hPa再分析温度、风场资料，通过统计分析发现陕西全省日最高温度变化具有很好的一致性，且在春季存在明显的6~28 d的波动。当6~28 d波动处于正位相时，850 hPa上陕西地区受偏南气流控制，且温度偏高，而波动处于负位相时，850 hPa上陕西地区为一高压反气旋控制，且温度明显降低。根据两者的对比，找到影响陕西地面日最高气温6~28 d变化的影响区。通过单点相关的方法，在6~28 d滤波的850 hPa温度场上找到与影响区温度超前15 d左右相关性好的关键区：65º~70ºN，40º~45ºE。进一步研究表明，6~28 d低频温度有明显的从关键区向影响区传播的趋势，并且与15 d后陕西地区日最高温度6~28 d变化相符合，对陕西地区春季未来15 d最高温度预报有一定的指示作用。
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