It has been reported by Nissan that battery longevity is most affected by battery temperature, and battery temperature by climate. I monitor my LEAF battery monthly for capacity and temperature using LeafSpy, and share below the temperature data for the past 5 months. We park the car in the shade at home, try to avoid parking on hot asphalt in the summer when out and about, charge during the cool hours, and do not fast charge. Car is used most days for about 15-20 miles.
Ambient average is calculated from historical data using the simple average of (max+min)/2
So at least for our use profile Nissan is correct to within a few degrees.