1. A full moon on Halloween is a fairly rare occurrence, happening every 18 or 19 years. The last Halloween full moon was in 2020. According to EarthSky, we can expect the next Halloween full moon to happen on October 31, 2039. In 2025, the moon on Halloween will be a waxing gibbous, approximately 70% illuminated. Does 2039 seem like a long time away?