Thailand has a warm tropical climate high in both temperature and humidity. The best time to visit Thailand is the cool season from November to end of February during which the maximum temperature is 30-35°C / 85-95°F and the humidity is at its lowest between 50% – 60%. It is also the season for several major Thai festivals like the Loi Krathong.
The summers (March till May) are very hot with temperatures soaring well over 40°C/105°F. It is perfect for a visit tothe northern provinces, but North-Eastern and Central Thailand tours are best avoided during this period.
The monsoons arrive in June and this season continues till the end of October (probably the wettest month). The rainy season is considered to be the best time to visit the islands in the south. July and August are often referred to as being the second peak season after winter (November till February end). The least popular months for Thailand tours are April to June and September to October.
Central (Bangkok, Kanchanaburi, Ayutthaya, Sukhothai):
Most Enchanting: October – March
Quite Enchanting: April – June
Rainy season: July to October. Take an umbrella and be prepared to change plans depending on weather.
North (Chiang Mai, Chiang Rai):
Most Enchanting: March
Quite Enchanting: April– June; November
Rainy Season: July – October. Take an umbrella and be prepared to change plans depending on weather.
From December – February the weather is cold and wet, not the kind of weather you might associate with Thailand! Take layers of clothing including a warm jacket, socks and a light woolen cap.
Upper Gulf of Siam (Hua-Hin):
Most Enchanting: October – May
Rainy season: June – September. Travel is not recommended.
Lower Gulf of Siam (Koh Samui):
Most Enchanting: May – September
Quite Enchanting: January – April
Rainy Season: October – December. Travel is not recommended.