Your question is a bit weird in it's formulation.
First, D&D 3.5 doesn't really use wind speed, it instead uses levels of wind strength, of which there are 7 (from "Light" to "Tornado"), and each level has assigned a range of wind speeds (from 0-10 mph for Light, to 175-300mph for Tornado).
Certain niche spells and effects do use wind speed in it's calculations, like Air Walk (where the wind blows the air walker 5 feet for each 5 miles per hour of wind speed), or when a ship is Driven by strong winds (making it move downwind at a speed in feet per round equal to twice the wind speed in miles per hour).
I'm guessing the player trying to increase the wind speed as high as possible is doing it because of one of these niche cases.
Most of the effects that affect wind speed don't really increase wind speed, they just increase the wind strength, which has a maximum at level 7 (tornado), which would cap wind speed at 300mph.
This can be achieved easily with a single casting of Control Winds, for example, as it raises the wind strength by 1 for every 3 caster levels.
If you wanted to break the 300mph barrier, your options are greatly reduced. As far as I know you would have 2 options:
- After achieving tornado level winds (300mph), use the psionic power Control Air, which is the only effect I know of that directly increases wind speed (instead of wind strength). That would allow you to increase the wind speed by another 60mph, for a total of 360mph.
- Just Wish for whatever speed you want, or use other "open-ended" effects to do it, Miracle, custom spells, custom magic items, etc....