*4.1. Definition of the Dry and Wet Season*

The identification of the warm/dry and cold/rainy seasons in Slovenia was not trivial due to sparse landscapes and different climatic conditions. Four regions were identified: (i) North East, the region with less rainfall; (ii) North West, the Alpine region; (iii) South West, the coastal region with Mediterranean climatic conditions; and (iv) the Central region, the pre-alpine that receives the highest rainfall (more than 3000 mm per year). The rain gauges in each region were classified accordingly (Figure 1). Using the average monthly rainfall and temperature data between 2007 and 2018 and applying the MSWB model, the length of the two seasons in each region was defined. Furthermore, using the aridity index, the ratio among the "no rain" intervals in each season was determined. This ratio resulted equal to 2, corresponding to a "no rain" interval of 48 h (set as minimum) in the warm season and 96 h in the cold season, respectively. Figure 2 shows the results of the analysis for the four considered regions. While the North East, South West and Central regions experience dry periods (AI ≥ 1) in the summer months (with diverse lengths), the North West part (Alpine area) has no dry period. Therefore, in North East, South West and Central regions, rainfall events were reconstructed using a "no-rain" period of 48 h and 96 h in the warm/dry and cold/rainy season, respectively. Conversely, in the North West region, rainfall events were always separated by 96 h.

**Figure 2.** Calculated aridity index for individual regions: (**a**) South West; (**b**) North West; (**c**) North East; (**d**) Central region. Green and red areas indicate the cold/rainy and the warm/dry months, respectively.
