Abstract: This study focused on the climatic conditions of the Liangpan tobacco-growing areas in Sichuan Province, integrating agricultural threshold temperatures and temperature-rainfall synergy to quantify matching differences under various guarantee rates, it quantitatively evaluated the spatial differentiation of temperature-precipitation matching under different climatic guarantee rates. The daily meteorological observation data from 1951 to 2021 of four typical regions(Yanbian, Yanyuan, Huili, and Yuexi) were used to quantify the spatiotemporal characteristics of key agricultural threshold temperatures (13℃, 15℃, 18℃, and 20℃) under different guarantee rates, and the temperature-rainfall synergy during the tobacco root elongation stage was systematically analyzed by the 5-day moving average method and empirical frequency method. The Temperature-Rainfall Matching Coefficient (TRMC) was introduced to quantify the synergy during the root elongation stage. The results showed that altitude was the primary influenced factor for the spatiotemporal differentiation of agricultural threshold temperatures. The initial dates of all threshold temperatures at an 80% guarantee rate were later than those at a 50% guarantee rate, and the regional sequence of initial dates was Yanbian > Huili > Yuexi > Yanyuan. The average temperature during the root elongation stage in each tobacco region increased with the rise of threshold temperature, showing the highest in Yanbian, the lowest in Yanyuan, and moderate in Yuexi and Huili. At an 80% guarantee rate, TRMC exhibited significant regional differences: Yanbian had sufficient heat but severe drought, with low TRMC and water as the main limiting factor; Yanyuan had relatively low temperature but abundant rainfall, and higher rainfall improved TRMC and offset the adverse effects of low temperature on root development; Huili presented low TRMC under low thresholds but significantly improved TRMC and better synergy under high thresholds; Yuexi maintained high TRMC under all thresholds with the optimal temperature-rainfall synergy. The initial dates of agricultural threshold temperatures at an 80% guarantee rate can be used as the core meteorological reference for tobacco transplanting. The initial dates of agricultural threshold temperatures at an 80% guarantee rate can be used as the core meteorological reference for tobacco transplanting in this region. Differentiated water management strategies should be implemented according to regional temperature-rainfall synergy in each tobacco area. This study provides a meteorological basis for determining the tobacco transplanting date and managing water during the root elongation stage in tobacco-growing areas of Liangpan region, and also offers methodological references for quantitative research on temperature-rainfall synergy during key crop growth periods.