As a my bow gets hoter the string tends to strrech thus the bow gets slower and the arrrow drops faster. That is also why you would get two different peak weights. THe yok can also strech from this and cause the same thing. something else to look at on those 100* days is the sun bright and on the cooler days is the sun less bright this can effect the way you view the sight pin and cause your point of impact to change hope this helps some.