Middle-season rice is an important food crop in southern rice areas of China, especially in Yunnan, the main rice-producing region. However, due to the impact of low temperature at the seedling stage and high or low temperature at the booting and heading stage of middle-season rice, the yield is not stable.Based on the data of yield factors of different middle-season rice varieties planted in the same ecological site in Jingdong County from 2009 to 2016, average development period was calculated using the data of development period measured in field during 2009-2016, and the average of meteorological factors (daily average temperature, daily maximum temperature, daily minimum temperature, and sunshine hours) and total precipitation were calculated. The correlation between meteorological factors in different development periods of each year and corresponding per unit area yield was analyzed. Temperature is the most important factor affecting rice yield. Sufficient light is beneficial to the increase in the number of grains per spike and thousand seed weight in the sowing-seedling emergence stage and milk maturity-maturity stage. Excessive precipitation will reduce the number of grains per spike in the booting-heading stage. Excessive precipitation decreases the number of filled grains per spike in the jointing-booting stage, and proper drainage helps increase the formation rate of ears. In this study, the main meteorological factors affecting rice yield were analyzed to provide scientific reference for rice production and management in this county in future
