I have flown in winds up to about 20mph, but that is when the direction is right down the runway. Cross winds speeds can be much less and still present a problem for new flyers. There is really no set speed that comes to mind, if you are hesitant, then it's for a reason. If you fly when you are comfortable, it makes it much easier on yourself and as you gain experience, you will find that you get more and more comfortable with the wind as your flight time increases.