Based on the daily meteorological data from 40 meteorological stations from 1961 to 2016, the thermal change characteristics of Sichuan Province were studied. We adopted the climatic tendency rate and the nonparametric Mann–Kendall statistical test to identify the temporal changes in the Sichuan Province thermal resources. Multiple regression equations for the thermal resource factors were constructed based on their longitude, latitude, and altitude. We also used a multivariate regression model with the residual modified by inverse distance weight interpolation to analyze the spatial variation of thermal resources.

The results showed that: the thermal conditions in Sichuan Province generally increased over the past 56 years and the annual average temperature, the annual average minimum temperature, the accumulated temperature above 0°C, and the accumulated temperature above 10°C had all increased by 0.204°C/10a, 0.267°C/10a, 58.48°C/10a, and 61.49°C/10a, respectively. The spatial distribution showed that the annual average temperature, the annual average minimum temperature, accumulated temperature above 0°C, and accumulated temperature above 10°C expanded from the southeast to northwest in Sichuan Province. The areas where the incremental changes in the annual average temperature and annual minimum temperature were the most significant were the northwest region of Sichuan Province, the Panzhihua-Xichang region, and the east region of Sichuan basin. The accumulated temperature above 0°C in the western Sichuan plain had increased significantly, while and the southeast region of Sichuan Province had the largest increase in accumulated temperature above 10°C. From 1961 to 2016, the frost-free period and the growing season for thermophilic crops became longer in Sichuan Province. The most obvious extended regions of the frost-free period were the northwest region, western Sichuan plain, and the northeast region of Sichuan Province. The area with significant extension of the growing season of thermophilic crops was Liangshan in the southwest region of Sichuan Province, where the thermal conditions for thermophilic crops improved gradually.

In the past 56 years, the temperature in Sichuan Province had generally increased, while the frost-free period and the growing season of warm crops were also extended. In general, agricultural thermal resources have increased in Sichuan Province and thermal resources have become more abundant in Sichuan basin, Pan-Xi region, and the northwest Sichuan plateau.