Ok so the spreadsheet looks like this.
I start with the temperature combinations.
sheet1.png
I have the min/max for each but only the average is relevant actually.
The on the right, I find the average annual temperature. It is an average of the maximum and minimum temperature.
My numbers are slightly different because I did not round them up this time. I guess I must have done that to save time. This time I can be more precise since Excel is going to calculate it.
Aridity index.
sheet2.png
The grey area represent redundant combinations. They are also present on the two other graph but I haven't greyed them.
I usually left them there, maybe to avoid having holes in the graph.
It is explained if the cells but these graph tells us what is the minimum threshold required to have a wet climate, steppe or desert.
Depending when the dry season is, or if there is even one to begin with, the formula for aridity is slightly different.
https://en.wikipedia.org/wiki/Aridity_index