Dry air and low humidity is very helpful to snowmaking and actually is as important as temperature.

The combination of humidity and temperature is called "Wet Bulb". It allows, through evaporative cooling, more water to be converted into snow than does moist air of the same temperature. Believe it or not, sometimes a resort can make better snow at 28 degrees and low humidity then at 21 degrees and high humidity.

In fact we have made snow as high as 38 degrees before although to be completely honest you are not making too much snow then and it really isn't worth the cost.