The climate in Cambodia is relatively consistent throughout the country--hot and humid. There are two distinct seasons: a dry season that lasts from November to May, and a rainy season lasting from June to October. The country has an average annual rainfall of between 50 and 75 inches with the southwestern mountains, the area with the highest rainfall, receiving nearly 200 inches per year. December to February are the coolest months of the year, when temperatures can drop to the mid to upper 60°F (25-27°C). April is the hottest month, when temperatures regularly exceed 100°F (40°C). The average relative humidity is 81%. During the rainy season, periodic flooding in Phnom Penh can make driving a problem due to the city's old and dysfunctional drainage system. Despite this, standing water usually drains away within a matter of hours.