Objective The soil moisture temporal stability is crucial for studying catchment hydrological processes, ecological conservation and agricultural management. However, few studies of the soil moisture spatiotemporal dynamics in complex terrain during wet-dry transitions were conducted.

Method This study investigated the temporal stability during different periods (wet seasons, dry seasons, and wet-to-dry transitional periods) using the Index of Temporal Stability (ITS). Through Redundancy Analysis (RDA) and Pearson correlation analysis, the influence of environmental factors was explored on the soil moisture temporal stability.

Result The results showed that the temporal stability of soil moisture was quite different during different periods and is influence by different factors. The soil moisture exhibited higher temporal stability during the wet seasons, primarily controlled by soil-terrain attributes, whereas it is relatively lower during other periods. The temporal stability during dry seasons was comprehensively influenced by many environmental factors with soil composition. The temporal stability during transitional periods was significantly affected by the preferential flow frequency and also controlled by soil-terrain attributes. There are two representative locations, Site 35 and Site 65, which can predict the catchment mean soil moisture with high accuracy (R² = 0.91).

Conclusion These findings enhance our understanding of catchment hydrological processes and contribute to a better comprehension of soil moisture temporal stability in forest catchments and the combined effects of their external environments.