The factor in the atmosphere that is most responsible for changes in an area’s temperatures and humidity levels is the movement of large air masses.
Air masses are large bodies of air that have uniform temperature and humidity characteristics. When these air masses move into a new area, they can significantly alter the local weather conditions, including temperature and humidity. For example, a warm, moist air mass can increase temperatures and humidity levels, while a cold, dry air mass can decrease them.
While other factors such as the density of air, amount of precipitation, and different types of cloud formations can also influence weather, the movement of air masses is a primary driver of significant and immediate changes in temperature and humidity.