Thailand welcomes visitors all year round, but the gap between "you can go" and "you should go" can be several months, and sometimes a choice of coast. We look at how the Thai seasons work and where to find sunshine when a tropical downpour is lashing the other side.

You've flown to Phuket in September because the flights were half the price of January's. There are red flags on the beach, big waves, and swimming is banned. The rain starts around noon and only stops by evening. Meanwhile, a friend of yours is on Koh Samui at the same time, with sunshine, calm seas and warm water. The secret is simple: Thailand has two coasts with different climates, and they run on different calendars.

Two Seas, Two Monsoons

Thailand is washed by two bodies of water: the Andaman Sea to the west (Phuket, Krabi and the Phi Phi Islands) and the Gulf of Thailand to the east (Koh Samui, Koh Tao, Koh Phangan, Pattaya and Koh Chang). The weather is shaped by two monsoons, which arrive from different directions at different times.

The southwest monsoon (May to October) brings moisture from the Indian Ocean and batters the Andaman coast. Phuket and Krabi get the bulk of their rain in these months.

The islands in the Gulf of Thailand are sheltered by the mountains of the peninsula and stay relatively dry. Pattaya gets more of it: it has less rain than Phuket in summer, but by September and October the downpours gather strength.

The northeast monsoon (roughly November to February) turns things around: moisture comes in from the South China Sea and pours down on the western shore of the Gulf of Thailand. Koh Samui gets its heaviest rain from October to December, while Phuket is already in its dry season.

That's why there's no universal "best month" for the whole of Thailand. But at almost any time of year, there's a coast where the beach weather is excellent.

Phuket and Krabi: November to April

The Andaman coast has Thailand's most beautiful beaches: white sand, turquoise water and limestone cliffs. But you pay for that beauty with a short window of perfect weather.

November to February is the best time. There's little rain, the sea is calm and underwater visibility is excellent. Daytime air temperatures are 29–32°C, and the water is 27–29°C. This is high season: hotels are full and prices are at their peak, but the weather is worth it.

March and April are still dry but very hot: the air heats up to 34–35°C and the humidity rises. The first downpours arrive towards the end of April. For those who cope well with heat, it's a perfectly workable option with slightly lower prices.

May to October is the rainy season. In July and August, Phuket gets up to 300 mm of rain a month. The rain usually falls in the afternoon or at night, and mornings can be sunny. But the main problem isn't the rain but the sea: waves on the west-facing beaches reach several metres, rip currents develop, and red flags go up on many beaches, meaning swimming is life-threatening.

For surfers, though, this is the best time: the waves at Kata and Bang Tao beaches work precisely in the rainy season.

Koh Samui, Koh Tao and Koh Phangan: A Calendar of Their Own

The islands of the Gulf of Thailand are the country's climate rebels. When it's pouring in Phuket, it's often dry and sunny here. But when Phuket's high season begins, Samui's rains reach their peak.

February to April is the best period. February is the driest month on Samui, with 30–65 mm of rain according to various sources and around five rainy days. The sea is calm, and visibility is good for snorkelling and diving.

May to September is a transition period. There is some rain, but it's much lighter than in Phuket at the same time. July and August are perfectly decent months for a beach holiday on Samui: around 100–120 mm of rain, which usually falls at night or early in the morning. September is the last relatively dry month before the rainy season.

October to December is the rainy season. It peaks in November, with between 280 and 490 mm of rain and 15–19 rainy days a month, depending on the source. The sea becomes murky and rough, and boat trips to the neighbouring islands may be cancelled. The first half of December is still wet, but by New Year the weather usually settles down.

That makes Samui an excellent alternative to Phuket in summer: while the Andaman coast is getting drenched, the Gulf of Thailand has perfectly comfortable beach weather.

Pattaya: Closer to Bangkok, Milder in Summer

Pattaya lies on the eastern shore of the Gulf of Thailand, but its seasons are more like Phuket's than Samui's, only the rain is lighter here and the sea calmer.

  • November to February is the best time. It's dry and not too hot (around 30–31°C), with minimal rain, about 30 mm a month. The water is 27–28°C.

  • March and April are hot: temperatures rise to 33–35°C. The rain starts towards the end of April.

  • May to August — the rain picks up, but not as sharply as in Phuket. May gets around 120 mm, and July–August about 180 mm. The showers are usually short and don't stop you swimming, as the sea in Pattaya is sheltered from big waves.

  • September and October — the peak of the rains: up to 250–260 mm a month and 14–15 rainy days. In these months, a beach holiday in Pattaya is at its least predictable.

For swimming, many people head to Koh Larn, an island 7 km offshore, where the water is cleaner and the beaches better than along Pattaya's city seafront.

Water Temperature: Always Warm

Unlike most of the world's resorts, Thailand has warm water all year round. The minimum is 27°C in December and January, and the maximum 30°C in April and May. The difference between seasons is just a couple of degrees.

Even in "cold" January the water is more comfortable than the Black Sea at the height of summer. The question isn't the water temperature but the state of the sea: waves, currents and murkiness after the rain are what decide whether it's worth going in.

Getting There From Russia

Direct scheduled flights from Moscow to Bangkok and Phuket are operated by Aeroflot, taking about 9–10 hours. In winter, Aeroflot also flies to Bangkok and Phuket from St Petersburg, Yekaterinburg, Novosibirsk, Krasnoyarsk, Irkutsk, Khabarovsk and Vladivostok.

S7 Airlines doesn't fly to Thailand from Moscow, but it does operate from Siberia and the Far East: from Irkutsk to Bangkok and Phuket, from Vladivostok to Bangkok (three times a week in winter) and, from October 27, 2026, from Novosibirsk to Phuket (with a technical stop in Irkutsk, taking about 10.5 hours).

In winter, Thailand is one of the most charter-heavy destinations from Russia. For winter 2026/27, charters to Phuket and Pattaya have been announced from 20 cities. PEGAS Touristik and Coral Travel fly their customers on Nordwind, while Anex, Intourist and FUN&SUN use AZUR air. PEGAS Touristik also has seat blocks on Siam Wings flights.

In summer there are far fewer charters: in summer 2026, Phuket was served mainly by Ikar (for PEGAS Touristik and Coral Travel packages) from Moscow, Yekaterinburg, Krasnoyarsk and Novosibirsk.

Direct return flights from Moscow to Phuket in the low season cost from 87,000–100,000 roubles per person (a guide based on summer 2026; check current prices before you travel).

Visas

Since September 15, 2026, Russians can stay in Thailand for up to 30 days without a visa: the temporary 60-day visa-free scheme has been scrapped, and a bilateral agreement between Russia and Thailand now applies. You'll need a passport valid for at least six months.

If necessary, the visa-free stay can be extended once for another 30 days at an immigration office for 1,900 baht (~$60). That makes a maximum of 60 days without a visa.

Before departure, you need to fill in the TDAC electronic arrival card.

Which Month to Choose

November to February — high season in Phuket, Krabi, Pattaya and Koh Chang. The best weather, calm seas and the most sunshine. But also the most tourists, so book early, especially for New Year and February dates.

February to April — the best time for Koh Samui, Koh Tao and Koh Phangan. The driest period on the Gulf islands, with good visibility for diving.

May to August — low season on the Andaman coast, but a perfectly good time for Samui and the Gulf islands. Hotel and package prices drop by a third to a half. If you don't mind an evening downpour, you'll get a great holiday at a reasonable price.

September and October — the riskiest time for a beach holiday. Waves and red flags in Phuket, peak rains in Pattaya. The exception is Samui in September: it's still a fairly dry month, and the island's rainy season starts in October.

If your holiday falls in these months, choose Samui in September or build in some spare days.

April — a compromise between seasons. It's already hot but still dry. It works for all the resorts, except for the very end of the month, when the first thunderstorms arrive on the Andaman coast.

Thailand is convenient because there's always somewhere to go: if it's raining on one coast, the sun is shining on the other. All you have to do is check the monsoon calendar and pick the right side.