Weather and climate models aren't some arbitrary curve-fitting; they're physically based using ridiculously detailed physical simulations of air movements and ocean currents, starting from an observed state and running the simulation forward.
Just because a set of predictions is based on a physical model does not necessarily make it a better set of predictions. Physical models are still hypotheses, in that the basic premises behind the model and even the construction of the model itself have not been demonstrated as an accurate representation of reality. It is not until the model turns out accurate predictions that are significantly better than random that the hypothesis stands a chance of being correct.
I'm a reservoir engineer for a large oil and gas company, and we actually avoid using physical models/simulations like these to book reserves because of how horribly they perform. Third-party reserves auditors also make this recommendation. And it's not like the oil and gas industry hasn't invested a tremendous amount of money into the best-performing forecasting methodologies available. But they are held to a much stricter standard of performance simply by way of return on investment.