Where the rubber hits the windshield
If you have not checked your windshield wiper operation lately, due to our dry weather, it is time! Consider that clear, unobstructed, visibility is at the top of the list, to safely operate your BMW. For that reason, your wipers should be checked regularly.
As with most of the rubber/composite materials on your car, these are subject to the stresses of heat, road grime, cold, etc.. So, they will crack, split, (all of those fun things), and will not keep your window clear.
Wipers should be replaced every 6 months, (or more) if necessary.
Enjoy your BMW, and please drive safely!