The primary factor that determines the climate of a region is latitude, which refers to the distance of a location from the equator. Latitude significantly influences the amount of solar energy received, affecting temperature and precipitation patterns. Regions near the equator tend to have a warmer and more consistent climate, while areas closer to the poles experience cooler temperatures and greater seasonal variations. Additionally, other factors such as altitude, ocean currents, and prevailing winds also play essential roles in shaping local climates, but latitude is the fundamental determinant that largely influences climate characteristics across the globe.