Hello
I am looking at the forecast for the city of London
https://www.windy.com/multimodel/51.516/-0.092?51.126,-0.092,8
On a 3 hour basis, I get this

On an hourly basis I get this

Look at the rainfall for the period.
There is either an issue with the row label (which should read mm/h) or there is an issue with the numbers (3 hours of 10mm/hours) should give 30mm for a 3 hours period