Number of days available for climatic review
| Parameter | Jan | Feb | Mar | Apr | May | Jun |
| Tmax | 615 | 560 | 617 | 594 | 616 | 593 |
| Tmin | 646 | 587 | 644 | 623 | 644 | 622 |
| Duration of sunshine | 275 | 299 | 301 | 288 | 272 | 256 |
| Precipitation | 124 | 114 | 124 | 121 | 126 | 120 |
| Humidity/Visibility | 120 | 110 | 119 | 114 | 117 | 112 |
| Parameter | Jul | Aug | Sep | Oct | Nov | Dec |
| Tmax | 615 | 612 | 594 | 614 | 590 | 618 |
| Tmin | 639 | 647 | 621 | 638 | 623 | 646 |
| Duration of sunshine | 331 | 338 | 350 | 362 | 297 | 300 |
| Precipitation | 127 | 129 | 122 | 123 | 120 | 124 |
| Humidity/Visibility | 118 | 118 | 114 | 113 | 115 | 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