The frequency of days with precipitation should not be considered as frequency of cloudy days. Beginning in April 1988 HAIL is also included under Snowfall. Therefore, some stations may show snowfall during the warm months. The average wind speed is based on the speed of the wind regardless of direction. If the direction is expressed numerically, the maximum speed is the highest one minute average value recorded by the observer.
Direction is given in tens of degrees clockwise from true North.
The total time that sunshine reaches the surface of the earth is expressed as the percentage of the maximum amount possible from sunrise to sunset with clear sky conditions. This table shows the mean number of days per category of cloudiness. The categories are determined for daylight hours only. The relative humidity is expressed as a percentage measure of the amount of moisture in the air compared to the maximum amount of moisture the air can hold at the same temperature and pressure. Average humidity values are given for selected morning and afternoon observations.