Unpredictable
As Tony said, the forecasts not very reliable. Since that is a fairly sort distance through there it isn't going to effect your total time a lot. If I was doing this trip, I would not worry too much about the current forecast. But watch the winds. A stiff breeze, blowing against the current down there, can make for some pretty nasty conditions. I would stay west of 90degrees until I hit the northern Yucatan coastline, which should keep you out of the worst of the loop. Then hug the Yucatan coast going through. Once through your home free. Are you going to do a turn around, or planning on spending hurricane season down there. Have a wonderful trip, and wish I was going too.