# How to calculate the daily average radiation

### Daily average radiation

The daily average radiation is measured for the hours the sun is up. It is up for discussion to take into account the first and last hours, because these hours often don't contribute fully to the average. Similar to the hourly radiation, the radiation values have to be multiplied:

${\displaystyle radiation_{daily}={\frac {\sum _{t=n}^{m}Q_{t}}{m-n+1}}\cdot 10000/3600}$,

where n is the first full hour with sun radiation and m is the last full hour with sun radiation.

## Also see

For more information on the KNMI historical weather data table and how to download this information please go to the Tutorial dutch model attributes (Heat Overlay)