NEWRY, Maine— An hour before dawn, Ian McCluskey adjusts his goggles and plunges the sleeve of his jacket into a spray of ice crystals arcing out of a nearby fan-shaped snow-making machine. Mr. McCluskey is testing the quality of machine-made snow—as the spray settles on his sleeve “you can tell whether you are getting wetter snowball snow, or something that is very dry and good for resurfacing a trail,” shouts Mr. McCluskey, a 28-year-old snow-making supervisor at Sunday River Resort in western Maine. On this night, the machine-made snow is clumpy and won’t spread evenly. The air is too warm and humid to run this brand-new automated snow-making machine, or snow gun, for more than a few minutes.

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