Laos has a hot and humid tropical climate. There are two seasons. The rainy season lasts from May until October while the much more pleasant dry season lasts from November until April. During the rainy season there is about 200 to 300 mm of rain a month and the high temperatures, averaging around 33 C during the day and around 24 C at night, makes this time the worst for a visit. The dry season is much more pleasant with days still close to 30 C and nights a nice 15 C to 18 C. Daytime in the period of March until May can be very hot in large parts of the country, with temperatures regularly exceeding 40 C. Mountainous areas, especially in the north, can get rather chilly during northern hemisphere winter, when northern winds blow from China.