Large data sets

Daily mean temperature

This is the average of the hourly temperature readings during a 24h period

Daily total rainfall

including solid precipitation (snow and hail) which are melted before being included, amounts less than 0.05mm are recorded as trace

Daily total sunshine

recorded to the nearest tenth of an hour

Daily mean wind direction and windspeed

In knots, averaged over 24hh from midnight to midnight. Mean wind directions are given as bearings and cardinal (compass) directions. The data for mean windspeed is also categorised according to the Beaufort scale

What is the Beaufort scale measured to?

1 - 5 (1 - 21 knots)

Daily maximum gust in knots

The highest instantaneous wind speed recorded. The direction from which the maximum gust was blowing is also recorded.

Daily maximum relative humidity

Given as a percentage of air saturation with water vapour. Relative humidity above 95% gives rise to misty and foggy conditions.

Daily mean cloud cover

measured in “oktas” or eighths of the sky covered by cloud

Daily mean pressure

Measured in hectopascals (hPa)