Isle of Portland





Number of days available for climatic review

ParameterJanFebMarAprMayJun
Tmax3028302580
Tmin3127312990
Duration of sunshine000000
Precipitation3136333290
Humidity/Visibility000000


ParameterJulAugSepOctNovDec
Tmax000102525
Tmin000142626
Duration of sunshine000000
Precipitation000143240
Humidity/Visibility0016039541040960


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.