I often play a variety of flute-like instruments outdoors. (flutes, bamboo/wood & metal; recorders, wood & plastic; whistles, metals & wood; fifes, piccolos, etc.) I would be less concerned with the temp affecting the instrument, and more concerned about how the instrument will be heard by the wedding party & guests. What, if any, instruments will you be performing with? If you are going to have a sound system, it probably won't matter. If not, I might suggest that you use an instrument which has a sound which will carry better than the average recorder.   I would probably be tempted to take with me a couple of choices of instruments. If tunable, tune as best you can beforehand (& with any other instruments you will be performing with). Just prior to playing, close all the holes & gently breathe air into the instrument so as to not be heard, but warm it a bit. In any case, before the performance begins, take note of which way the wind blows & attempt to turn yourself so that the wind cannot go up the instrument & block your air from going out.