ORIGINAL: Charlie P.
I prefer 5 to 10 mph, will take more if it's not gusty or changable. Dead calm makes take-offs and landings harder. I have flown a full-symmetrical wing in 25 mph but can't say it was easy or relaxing.
Depends a LOT on the model I have at the field at the time. My Hot Stik is much more wind sensitive than any of my other models. It gets tossed around like a leaf when I slow down for a landing.
With much dihedral or a flat-bottomed wing it adds some complication. 12 to 15 mph would be about as much as a trainer should attempt under fledgeling thumbs.
Last weekend no-one at my club flew... except me
I have no idea as to how windy it was (speed) But on Sunday (club meeting day) a couple of the guys showed up for the meeting. I asked them if they were going to fly. They all said it was to windy. So I pull the Hobbico Avistar I am setting up to train my daughter on. The .40 LA just made headway into the wind and hauled the mail on the downline. I treid to tell the others that if we were in the Midwest this would be a beautiful flying day. I have gotten to where I refuse to be grounded because the conditions are not "ideal". I just have many planes for many different conditions of flying.