How we measure cloud amounts
This Met Office article explains how cloud cover is measured in oktas or eighths of the sky.
In meteorology, cloud cover is measured in oktas, or eighths of the sky.
If you look up at the sky, and mentally divide it into eight boxes, then imagine all the cloud you can see squashed into these boxes. How many boxes does the cloud fill? This is how many oktas of cloud there are.
- 0 oktas represents the complete absence of cloud
- 1 okta represents a cloud amount of 1 eighth or less, but not zero
- 7 oktas represents a cloud amount of 7 eighths or more, but not full cloud cover
- 8 oktas represents full cloud cover with no breaks
We also use terminology to convey generally how cloudy it is, for example scattered cloud refers to 3 to 4 oktas where about half the sky is covered, broken cloud is 5 to 7 oktas where much of the sky is covered and overcast is 8 oktas of cloud with no breaks in the cloud at all.
© Met Office
