This mystery can be solved only with more information as maples drop leaves in spring for many reasons. My first thought is too much water as you mentioned rain and wind. If your soil drains poorly and there is a lot of rain the new growth turning yellow in the photo you sent could be the plant is stressed from wet soil.  Another cause would be a disease or wilt but from the way the tree put on new spring growth I am going to guess too much water after a spring down pour and cool weather. You did not mention where you garden but some areas of the US have experienced a lot of rain this spring and also late frosts that can cause leaf drop. If your region had a warm spell that caused new leaves to emerge followed by a late frost in April or May then the cold weather could be causing the new leaves to drop from the plant.  My suggestion is to wait and see if the problem disappears with dryer weather as summer arrives. You can always prune off the thin or weak branches that are drooping the most. This will shape up the tree and give it less foliage to support. Do not remove more than one fourth of the branches. If the leaves curl and turn yellow or if entire branches die back then this indicates a disease such as fusarium wilt which is much more serious and difficult to treat. There are fungicides available to try and treat fungal diseases of the soil, but they are not very effective.  A wait and see approach is best here.  Keep growing, Marianne Binetti