World

North America

O’Hare Intl. Airport (205m)





Number of days available for climatic review

ParameterJanFebMarAprMayJun
Tmax172615601720167117091669
Tmin173315621730167117141669
Duration of sunshine93576260124150
Precipitation186169187181186180
Humidity/Visibility184166184177182177


ParameterJulAugSepOctNovDec
Tmax172417251700175317041771
Tmin173117261705175717051771
Duration of sunshine1551241201249093
Precipitation188190210215210217
Humidity/Visibility182184205208204215


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.

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