Thailand in July: what to expect

July sits in the middle of the southwest monsoon, so the country splits in two. The Andaman coast — Phuket, Krabi, Koh Lanta, Khao Lak — takes the full force: heavy rain, big swell, red-flag beaches and boat trips that cancel. The Gulf islands of Koh Samui, Koh Phangan and Koh Tao run on the opposite rhythm and are usually dry and calm through July, which is why they are the pick this month.

Bangkok and the centre stay hot and humid, with rain arriving in short, heavy afternoon bursts rather than all-day drizzle. The north — Chiang Mai, Chiang Rai, Pai — is green and wet, with cooler mornings and trails that turn muddy. Expect roughly 30–33 °C by day in most places, a few degrees cooler in the northern hills at night.

July is mid-season, not peak. The crowds that matter are on the Gulf islands: European and Australian school holidays push Samui, Phangan and Tao toward their busiest and priciest weeks of the year, so book ferries and beds early. Bangkok and the north stay quieter and cheaper than the December–February peak.

On the Andaman side it is the opposite story. Resorts in Phuket, Krabi and Koh Lanta discount heavily to fill rooms in the rain, so this is a month for cheap beach hotels if you accept that swimming and island-hopping may not happen. Domestic flights and trains are easy to book at short notice outside the full-moon dates.

The fixed point is the July full moon, when Asarnha Bucha and Khao Phansa fall on consecutive days. Asarnha Bucha marks the Buddha's first sermon; Khao Phansa begins Buddhist Lent, when monks traditionally stay in one temple for three months. Temples hold candlelit processions and merit-making, and alcohol sales are banned nationwide on both days — bars close and shops stop selling beer.

The full moon also brings the monthly Full Moon Party on Koh Phangan, which fills ferries and rooms on the Gulf islands around the same dates. Late July carries royal and memorial days (28 July), when some government offices and banks close but travel is largely unaffected.

Head for the Gulf. Koh Samui, Koh Phangan and Koh Tao are dry and calm, with good diving around Tao and easy ferries between them. This is the month the Gulf coast earns its reputation.

Bangkok works well as a base: temples, markets and food are indoors or short hops, and the rain usually clears within an hour. Pair it with Kanchanaburi or Ayutthaya for day trips. In the north, Chiang Mai and Chiang Rai are lush and quiet, though Doi Inthanon and hill trails are muddy — check conditions before hiking.

Avoid the Andaman coast for beach time. Phuket and Krabi still function, but expect cancelled boat trips, red flags and closed dive sites. If you are already booked there, plan around markets, cooking classes and spa time rather than the sea.

Pack for heat, humidity and sudden rain. A light rain shell beats an umbrella in the wind, and quick-dry clothing is more comfortable than cotton. Reef-safe sunscreen, insect repellent and a dry bag for phones and passports cover the monsoon basics. Add a light layer for air-conditioned buses and northern nights, and shoes with grip if you plan to walk in the hills.

June sets up the same pattern with fewer school-holiday crowds and lower Gulf prices. August repeats July almost exactly: Samui, Phangan and Tao stay the dry choice while the west coast remains rough. September is the wettest month in Bangkok and on the Andaman coast, with flooding in low areas — only worth it for the lowest prices of the year.