Superstition Mountain wedding - which month is best?

Hi everyone, my fiancé and I are planning a wedding with 50-100 people in Superstition Mountain, and we can't decide which month to have it in. We just moved to Phoenix, so we are not familiar with what the weather is like. I want to have it in early December, starting in the late afternoon going into the evening, so we catch the sunset and are able to see the stars as well. My fiancé wants to have it next May, because he thinks December will be too cold for people to be outside here at night, and that it will be harder for people to travel out of NY/NJ because of snow, and he doesn't want people huddled awkwardly around heaters if it's in December. Is it true that early December will be too cold at the bottom of Superstition Mountain later on in the day, or would it be okay? Is late May okay to have a wedding here later on in the day, or does it get hot? Any insight is helpful!