Thailand has a tropical climate with a high degree of humidity. There are three distinct seasons, namely
Hot season - March to May
Rainy season - May to October
Cool (relative !) season - November to February
Average temperature is 30 degrees centigrade, though temperates will frequently rise to 36-38 degrees in the shade during the hot season. The temperature is the sun is frequently much hotter and precautions against sunburn are strongly recommended, especially when spending time on the beach. Night time temperatures rarely fall much below 23-24 degrees.
Rainfall tends to comprise short, but excedingly heavy, showers. These serve to cool the air and reduce the humidity. During the rainy season the drainage systems are frequently unable to cope with the amount of rain, leading to localised flooding everywhere, including cities such as Bangkok, and causing disruption to road and rail services.
Note that temperatures in the mountainous north can be much cooler, especially in the evenings.
Updated 3rd May 1999