When is too windy? When I set my plane down to fuel it and it takes off by itself!! I think that a lot depends on the plane and your experience level. On really windy days I love to fly my Twist or -Can-Do. I love to go backwards down the length of the runway or just hold a hover for as long as I can. Nothing like a "zero roll landing." The higher the winds, the better. Other planes like my Zero, I like to have a little lighter wind. I don't recommend a lot of trainers on extremely windy days, especially if it's a cross wind. If the wind is too high, I won't do much instruction - it's more of a fight with the plane and does not make flying fun for the student. My more experienced students (post solo), I will take them up and show them how to handle the wind, most often when I teach them how to do cross wind landings.