These are basic instructions for a mitred granny square for use as a temperature blanket.

For the middle ( rainfall) I used cream, 3 shades of grey and black
(no rain, 1-7mm, 8-14mm, 15-21mm, 22-30mm)

My temperature range was from minus 2 to 40 degrees Celsius in 2 degree increments for each colour. You should only need 1 ball of each colour for the very high and very low temperatures and 2 balls for all other temperatures. This, of course, is just an estimation as the weather temperatures will be different everywhere.

Individual squares will be approximately 3 x 3 inches.