They are guesses. Educated guesses, but they are still guesses.
I give them much more credit than that. Like when they say it's 80% change of rain. Is that a "guess" since there is a chance it will not rain?
The amount of differential math and the number of weather related parameters in these weather models is mind boggling. Predictions are based upon data and "most likely scenarios". That is not even in the same ballpark as a "guess". Of course, when the hurricane is many days out, minor differences in reality and the models will change its target hit spot more drastically, but they still always have a good model as to how the system is going to behave and where it will want to move towards, and as it gets close, really zero in its exact path.