For identification of key stations, first the correlations of monthly precipitation among the stations were computed for the period 1950–2010, considering all calendar months together. Then the correlations above 0.80 (p ≤ 0.05) in the matrix were identified. This correlation matrix is shown in Table 2. The correlations above 0.80 are highlighted in bold text. For monthly precipitation, the stations 79023 (Polkemmet) and 79046 (Wartook reservoir) showed the highest number of correlations above 0.80 with the rest of the stations in the study area. Therefore, one of these stations, in this case station 79046, was selected as the first key station for monthly precipitation. The stations which displayed correlations above 0.80 with station 79046 (first key station) were identified as the member stations of the first cluster. These member stations were 79014, 79019, 79023, 79026, 79028, 79034, 90173, 79074, 79079, 79080, 89003 and 89085.
Bold correlations are above the correlation threshold 0.80.