Malaysia is a tropical country, meaning that it is hot and humid for most of the year. There are two seasons on the Malaysian peninsula: wet and dry. The times of the seasons vary depending on the coast. The dry season along the west coast runs from November to March. The wet season sees frequent storms and showers, though they are often fairly short. The dry season on the east coast is from March to October. There are often heavy rains during the wet season, and it can be difficult, sometimes impossible, to reach the islands. A large number of beach resorts close for the wet season.
Temperatures in the mountains are typically cooler than lower-lying areas; be prepared and take a couple of sweaters, especially for the evening times.
March to October is generally the dry season in Sabah and Sarawak. Showers can occur, however, at any time of the year.