Koh Phi Phi's climate is tropical and warm throughout the year. The northeast monsoon from November into January is wonderful, with breezy clear days and fragrant cool nights. From February to May the breezes end, and the weather is at its best. From November to May, Phi Phi Island has 26 sunny days per month.
The southwest monsoon, from late May to October, brings rain and winds to the west coast of southern Thailand, but there are still 20 sunny days per month. Most often it's only a cool, late afternoon shower, but there can be rainy days on Koh Phi Phi. Seas can be quite rough during this season and swimmers should be careful.
There are 2 very hot periods of weather on Phi Phi Island, the first between April and May when the average temperatures range from 30 to 36ºC and only the occasional tropical thunderstorm brings relief from the heat. It is also very hot between September and October but the frequent rainfall has a wonderful cooling effect.
Tourist High Season is from November to April. However, it's best to avoid December and January if possible, as this is Peak Season, when accommodation can be hard to find and is expensive, particularly around Christmas and New Year, and Phi Phi's dive sites are very crowded.
Whether you are coming to Thailand for diving or not, we recommend you try to come from February to April. There are less tourists here, accommodation is much better value-for-money, the weather is at its best, and the seas their calmest. The dive sites around Koh Phi Phi, Hin Daeng and Koh Ha are less crowded, and it's your optimum time to see something special, as it's whale shark and manta ray season.