Climatic regions are determined less on the basis of temperature than on rainfall, which varies regionally from less than  to more than  per year. Almost all of the rain falls during the rainy season, which is usually from April to December, but varies in length from seven to nine months. In general, rainfall is much heavier on the Caribbean than on the Pacific side of the continental divide. The annual average in Panama City is little more than half of that in Colón. Although rainy-season thunderstorms are common, the country is outside the hurricane belt.