With a few exceptions, wherever and whenever you travel in Southeast Asia, you are likely to encounter hot and humid weather. All of Southeast Asia lies within the tropics, and the countries closest to the equator -- Singapore, Malaysia, Indonesia, and southern Thailand -- have the hottest annual temperatures. Vietnam, Laos, Cambodia, and the rest of Thailand located 10 to 20 degrees above the equator also have high humidity but slightly cooler temperatures. The mountainous northern regions of Thailand, Laos, and Vietnam get pretty chilly during the winter months between November and March, so bring a pullover.
Monsoon winds make weather patterns confusing to keep track of. The basic rule of thumb is this: Between the months of October and February, winds from the northeast create heavy rainfall and rough seas along the eastern coasts of Vietnam, Cambodia, Thailand (including Koh Samui), Malaysia, and Singapore; however, western coasts along Thailand (including Phuket) and Malaysia are peaceful and calm. In May, the winds shift, bringing rains and swelling seas from the northwest down upon the western coast of Thailand and Malaysia until October. Nearly every place has a dry and hot spell in March and April -- Bangkok swelters! The cooler months of October through March are also the most pleasant times to visit Hong Kong, while the most rain usually falls between July and September during typhoon season.
Singapore and Malaysia are hot and humid year-round, with annual average maximum and minimum daily temperatures of 90°F and 72°F (32°C and 22°C) and year-round humidity above 90%. Most major cities are located at or near sea level, where average daytime temperatures are in the range of 80° to 90°F (27°-32°C) year-round. The best way to escape the heat and humidity is to head for the hills and mountains in the higher-altitude regions of Thailand, Malaysia, Vietnam, and Laos.
Holidays & Festivals -- Some of the holidays celebrated in Southeast Asia might affect your vacation plans, either positively or negatively. Wherever you are, you won't want to miss Chinese New Year or the many lunar festivals and myriad events like dragon-boat races and small Buddhist fetes, but some holidays simply mean that businesses and attractions are closed.
