The Baidu index (BI) of allergic rhinitis (AR), namely AR-BI, and the near surface observations of meteorological elements from 2021 to 2023 are used to evaluate the impact of changes in the meteorological elements on the incidence rate of AR in China. The results are as follows. (1) The analyses of changes in the meteorological elements and synoptic processes reveal a good correspondence between the rapid increase of AR-BI and early cold air activities during the shift season from autumn to winter. The rapid and significant decrease in the daily minimum relative humidity (RH), daily minimum specific humidity and daily minimum equivalent potential temperature during the cold air intrusion is synchronized with the rapid increase of the AR-BI from its background value. (2) During the first or early cold air activities each year, the air humidity decreases rapidly and significantly from the range that is more suitable for the human body in summer and autumn (RH higher than 40%), which may damage the nasal mucosa and could be the main cause of the high incidence of AR during the shift season from autumn to winter, resulting in the period with a high AR-BI from early August to mid-September each year. (3) The influence area of the cold air gradually expands from the north to the south over China during the shift season from autumn to winter, and the dry and cold air with lower humidity also gradually advances from the north to the south, resulting in the beginning and ending times of the AR-BI peak (i.e. the high incidence period of AR) gradually delayed from high latitudes to low latitudes. (4) The variability of the AR-BI is significantly higher in the north than in the south. Compared with the southern region, the cold air has a more significant impact on the northern region, resulting in lower specific humidity and a greater decrease of air humidity in the northern cities, which may lead to a higher incidence rate of AR in the north.