Number of days available for climatic review
| Parameter | Jan | Feb | Mar | Apr | May | Jun |
| Tmax | 769 | 700 | 772 | 745 | 771 | 742 |
| Tmin | 769 | 701 | 772 | 746 | 770 | 744 |
| Duration of sunshine | 296 | 326 | 233 | 344 | 289 | 315 |
| Precipitation | 128 | 113 | 124 | 121 | 127 | 119 |
| Humidity/Visibility | 119 | 109 | 118 | 112 | 115 | 109 |
| Parameter | Jul | Aug | Sep | Oct | Nov | Dec |
| Tmax | 771 | 768 | 748 | 769 | 741 | 770 |
| Tmin | 765 | 771 | 745 | 763 | 747 | 771 |
| Duration of sunshine | 328 | 328 | 376 | 349 | 323 | 360 |
| Precipitation | 127 | 128 | 123 | 124 | 122 | 124 |
| Humidity/Visibility | 118 | 115 | 113 | 111 | 114 | 119 |
Climate data is usually derived from meteorological data of a certain number of years. The actual number of recorded years may vary from only a couple to 50 years or more. The quality of climate data depends on the number of available recorded years. Fewer years means less reliable data. The standart-period for reliable climate data is 30 years. For example, the mean monthly temperature for, let's say January, would ideally calculated from a total number of 930 recorded January-days. However, the usual number of recorded days is much smaller. The table above shows the actual number of recorded days for every parameter measured. |
Alor Setar