*d*<sup>1</sup> = 1.432788, *d*<sup>2</sup> = 0.189269 *d*<sup>3</sup> = 0.001308

According to the criteria of McKee et al. [7], severe and extreme droughts correspond to categories of negative SPI (below-average precipitation amount), as shown in Table 1.


**Table 1.** Climate classification according to the SPI values.
