Your post was also moved to the Folder subforum, so I'm copying my reply there to this subforum:

Aero drag goes as the square of wind velocity and power is proportional to the drag times the ground velocity. So in a 20 mph headwind the required power is proportional to 30^2 x 20 or 18000. That's the same as if you were riding 26.2 mph with no wind at all (26.2^3 = 18000). Of course that's assuming that aero drag was the only force working against you (no rolling resistance, gradient, mech. inefficiency) so in practice your equivalent speed without wind would be a little less - maybe 25 mph or so.

If you can't go close to 25 mph using the same level of effort then I do question whether the wind was really that strong. Keep in mind that the wind speed down near the ground is usually significantly reduced. So your wheels, legs, and lower part of the bike may have been seeing a wind speed of less than 20 mph even if your face was getting the full 20 mph headwind.