Kerala's climate is sultry. Summers are hot, but winters are pleasant. For the best weather, visit during the relatively cool season, between October and February. This is also a good time to see some of the more interesting festivals. March, April, and May are hot and humid, though the hill stations of Thekkady and Munnar are still pleasant, even without air-conditioning. Heavy rains fall between June and mid-August, swallowing up most of the beaches and more than a few roads in low-lying areas. A second monsoon sweeps in in mid-October and lasts through December, bringing thunder, lightning, and afternoon showers. Crowds at this time are at a minimum and hotel rates are slashed. Monsoon season is also supposed to be the best time for ayurvedic treatments. Fall also brings the major harvest festival called Onam, during which snakeboat races are run.