The 1 in 10 days of air temp <0 = 12 and the actual days = 15, so 3 days can be considered in any assessment. For the snow days 1 in 10 = 3 and the actual is 5, so 2 days could be considered.
The days (dates) are the same for both measurements.
Are they assessed as 3 days for the air temp plus 2 days for the snow or are the 3 air days only to be considered as they form the largest difference between actual days and 1 in 10?