Thailand in May: Weather, Crowds and What to Expect

May marks the start of Thailand’s southwest monsoon on the Andaman Coast, but the Gulf Coast remains dry and sunny. This split makes May an excellent month for budget-conscious travellers who focus on the right side of the country. Prices drop sharply, crowds thin out, and the Gulf islands offer peak conditions without peak pricing.

Weather by Region

Bangkok is hot (33-36°C) and increasingly humid as the monsoon approaches. Afternoon thunderstorms become more frequent, typically lasting 1-2 hours before clearing. Mornings are usually dry and usable for sightseeing. The rain provides welcome relief from April’s heat.

Chiang Mai and the north see the end of burning season as rains begin. Air quality improves dramatically compared to March-April. Temperatures remain warm (30-34°C) with afternoon showers. The surrounding mountains turn green as the rains arrive, and waterfalls begin to flow at full volume.

Andaman Coast (Phuket, Krabi, Koh Phi Phi) enters monsoon season. The Similan Islands close on May 1 and remain closed until November. Seas become rougher, particularly on west-facing beaches. Some smaller islands reduce ferry services. However, Phuket and Krabi town remain fully operational — it rains heavily for 1-3 hours in the afternoon, not all day.

Gulf Coast (Koh Samui, Koh Phangan, Koh Tao) is dry and calm. May through August is actually an excellent period for the Gulf islands — they operate on the opposite monsoon cycle to the Andaman side. Koh Samui has warm, clear seas and significantly lower prices than January-February.

Island Access

Koh Lipe ferry services from Pak Bara stop in May and do not resume until November. The island remains accessible by speedboat from Langkawi (Malaysia) but public ferry services are suspended. Plan Koh Lipe visits for November-April only. Koh Lanta, Koh Phi Phi, and Phuket maintain year-round ferry connections, though services reduce in frequency.

Festivals and Events

The Royal Ploughing Ceremony (Phrara Raek Na Khwan) takes place in early May at Sanam Luang in Bangkok. This ancient Brahmin ritual marks the start of the rice-growing season. The King’s representative ploughs a ceremonial furrow and oxen choose from offerings to predict the harvest. It is a brief but culturally significant event dating back centuries.

Visakha Bucha Day (full moon of the sixth lunar month, usually May) is one of Buddhism’s most sacred days, marking the birth, enlightenment, and death of the Buddha. Temples hold candlelit processions. Alcohol sales are banned for 24 hours.

Diving

With the Similans closed, Andaman diving shifts to sites around Phuket that remain accessible — Shark Point, Anemone Reef, and the King Cruiser wreck still run weather-dependent trips. Gulf side diving at Koh Tao and Sail Rock is excellent in May with warm water and good visibility. May is a solid month for PADI certifications at Koh Tao’s numerous dive schools.

Prices and Crowds

May is the start of low season pricing. Andaman Coast resorts drop rates by 30-50% compared to peak season. Gulf Coast prices are moderate — lower than January-February but not as cheap as the Andaman side, since the Gulf islands are still in their good weather window. Flights to Thailand from Europe and Australia are significantly cheaper.

Where to Go in Thailand in May

• Bangkok: Bangkok city guide
• Chiang Mai: Chiang Mai guide
• Phuket: Phuket guide
• Koh Samui: Koh Samui guide
• Koh Phangan: Koh Phangan guide
• Krabi: Krabi guide

Planning

See the best time to visit Thailand for a full seasonal comparison, or the Thailand budget guide for cost planning.