Number of days available for climatic review
| Parameter | Jan | Feb | Mar | Apr | May | Jun |
| Tmax | 273 | 246 | 273 | 260 | 268 | 256 |
| Tmin | 217 | 197 | 235 | 223 | 223 | 211 |
| Duration of sunshine | 0 | 0 | 0 | 0 | 0 | 0 |
| Precipitation | 96 | 85 | 86 | 66 | 62 | 72 |
| Humidity/Visibility | 20 | 18 | 21 | 12 | 11 | 18 |
| Parameter | Jul | Aug | Sep | Oct | Nov | Dec |
| Tmax | 255 | 248 | 243 | 258 | 262 | 265 |
| Tmin | 217 | 217 | 210 | 217 | 227 | 228 |
| Duration of sunshine | 0 | 0 | 0 | 0 | 0 | 0 |
| Precipitation | 93 | 93 | 88 | 80 | 102 | 122 |
| Humidity/Visibility | 18 | 17 | 18 | 15 | 17 | 15 |
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