Is it normal for a fully leaved ASH tree to noticeably shed leaves in early summer?

I believe my tree is over 80 years old and appears to be in great shape, growing larger each year. I never noticed pieces of yellow-shed leaves before, but weather has been erratic this year, ie, flooding rain uprooting many old trees in the area during the spring and now extremes of hot and cold temperature. Are yellow leaves a sign of too much water or too little? Thanks.