We went to DL in February 2016, for a week, and they cancelled the fireworks every night for wind. It was a bummer. It would usually not even feel windy, but apparently there was more wind higher up in the atmosphere from us at ground level.
I do not question the wisdom of the cancellations, of course. A few times we were on Main St, waiting and hoping, they wait until last minute to cancel, hoping to get them off.