Estimating the future risk of sediment disasters in a changing climate has been one of essential topics in recent decades. Some effects have been made to assess the future change of landslide alerts in Japan in a changing climate with the application of the critical line (CL for abbreviation) method. The critical line method utilizes a parametric curve of snake line, composed of hourly precipitation (P) and soil-water index (SWI), to reflect the effects of short-term rainfall and long-term soil wetness. The geometric feature of a snake line is highly affected by rainfall pattern, e.g., duration, peak intensity, and etc. The analysis of Clausius-Clapeyron scaling shows that extreme precipitation could be related to ground air temperature that can alter the capacity of water vapor in the atmosphere. In this study, we further extend the concept of scaling analysis to soil-water index for examining the effect of ground air temperature on the maximum range of snake line. We propose two exponential scaling relations for precipitation and soil-water index in terms of ground air temperature to assess the maximum range of snake line under climate change impact with a focus on the target area of the Rokko Mountain with case study of some scenarios.