Number of days available for climatic review
| Paramètre | jan | fev | mar | avr | mai | juin |
| Tmax | 1228 | 1123 | 1236 | 1195 | 1235 | 1191 |
| Tmin | 1230 | 1120 | 1229 | 1195 | 1232 | 1187 |
| Durée d’insolation | 274 | 278 | 302 | 325 | 276 | 258 |
| Précipitation | 155 | 141 | 157 | 153 | 157 | 150 |
| Humidité/Visibilité | 151 | 138 | 149 | 145 | 148 | 144 |
| Paramètre | juillet | août | sep | oct | nov | déc |
| Tmax | 1235 | 1233 | 1221 | 1252 | 1223 | 1268 |
| Tmin | 1227 | 1238 | 1223 | 1249 | 1227 | 1266 |
| Durée d’insolation | 301 | 308 | 379 | 394 | 325 | 332 |
| Précipitation | 159 | 161 | 182 | 185 | 180 | 186 |
| Humidité/Visibilité | 149 | 152 | 171 | 172 | 173 | 181 |
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