First things first. Definitely do a compass calibration and reset anything you can. It's not hard to do, and the app steps you through it. Like Tinmania says, the MP uses data from it's correction pitch, yaw, power settings v. GPS apparent position change to decide if there are strong winds or not. It does not have the sophistication of larger aircraft that can scan the ground to determine ground speed v. air speed and direction. You might want to be sure the downward sensors are clean. I had a friend who put a big red, one meter long ribbon on the back of his quad, so he could see it better as it flew. Had to take it off, because the quad kept "seeing" the ribbon fluttering during certain maneuvers and taking odd maneuvers as a result. Great idea, but not so good in real-life execution. A bit of grass or other debris near a sensor could cause erroneous data. Something that might help you zero in on what the issue is, is to see if you can figure out if there's a specific flight maneuver that makes the warning come up. Does it happen when you're turning, hovering, flying fast, slow, straight line, climbing, etc, etc. And one last thing, just a thought I had. Have you crashed your quad hard, ever? One of the arms could conceivably be out of alignment, or doesn't fully extend due to damage, causing the quad to have to compensate with prop RPMs, and interpreting that as wind speed. Not likely, but there's a chance.
