| Month | Highest mean total PET (mm) | Observed year | Coefficient of determination (%) |
| April | 152.7 | 2010 | 78.8 |
| May | 197.1 | 2008 | 66.73 |
| June | 186.2 | 2008 | 55.13 |
| July | 205.5 | 2007 | 10.37 |
| August | 180.6 | 2008 | 56.87 |
| September | 131.8 | 2011 | 49.19 |