Weather forecasting leaves a lot to be desired, surely in this day and age they can get it a little closer that as you have stated.
I used to travel the USA and central America on Privately owned motor yachts in the late 90's we used to use weather routing out of New York. They were pretty dam accurate forecasting weather on our trips at sea, we would leave from Ft Lauderdale Florida to Colon (panama) and they would forecast the weather spot on for the 4-5 day trip.