Rain and cooler temperatures could impact Halloween festivities in several regions. In the Northwest and Southwest, wet conditions may require umbrellas and rain jackets, with snow posing additional challenges in the Sierra Nevada. The Midwest could see scattered showers and thunderstorms, potentially disrupting outdoor activities. In the South, the lower Mississippi Valley may experience wet weather, while the Northeast is expected to remain largely unaffected. Parents and trick-or-treaters should prepare for varying conditions depending on their location.