Thailand is warm all year, but what you should wear changes with the season, the region and the place you are visiting. A linen shirt that is perfect for a Bangkok market will not get you into the Grand Palace, and it will not keep you warm on a northern mountain top in December. This guide covers what to pack for each season and what to wear at temples, rooftop bars and beaches.
Thailand's Three Seasons at a Glance
The Thai Meteorological Department (TMD) divides the year into three seasons. The dates move a little each year: in 2026, TMD declared that the rainy season started on 15 May.
| Season | Months | Typical weather | What to pack |
|---|---|---|---|
| Hot | Mid-February to mid-May | Highs usually 35–39 °C; some days pass 40 °C | Loose, light clothes, sun hat, sunglasses |
| Rainy | Mid-May to mid-October | Hot and humid, with heavy showers; in Bangkok, September and October are the wettest months | Quick-dry clothes, rain jacket, shoes with grip |
| Cool | Mid-October to mid-February | Little rain in Bangkok from November to February; cool nights in the north, cold on mountain tops | Light clothes, plus warm layers for the north |
The temperature and rainfall figures below are 1991–2020 averages from TMD weather stations, as published by the World Meteorological Organization. They are averages, not forecasts.
What to Wear in the Hot Season
In Bangkok, the average daily high in April is 35.7 °C, and even the average night-time low is 27.2 °C, so the nights stay hot. Chiang Mai reaches an average high of 36.7 °C in April.
- Loose shirts, trousers and skirts in cotton or linen, which let air move around your body.
- A wide-brimmed hat and sunglasses.
- Light sandals or breathable walking shoes.
- A thin long-sleeved shirt or a large scarf. It protects your arms from the sun and covers your shoulders at a temple.
Drink water often, and rest in the shade or in air conditioning around midday. Heat stroke can cause confusion and hot, dry skin; for a medical emergency, call 1669.
March and April are also the smoke season in the north: in April 2026, Chiang Mai was declared a disaster zone for air pollution. Check PM2.5 levels on the free Air4Thai or IQAir AirVisual apps before a day outdoors.
What to Wear in the Rainy Season
Rain usually comes as heavy showers rather than all-day drizzle. In Bangkok, September is the wettest month, with about 336 mm of rain on average but only about 18 rain days, so many days stay partly dry. For 2026, TMD expected the rains in upper Thailand to end around mid-October. On the Gulf side of the south (Koh Samui, Nakhon Si Thammarat and Songkhla), the rain continues until December.
- Quick-dry shirts, shorts or light trousers that dry overnight.
- A light rain jacket or a compact umbrella in your day bag.
- Sandals or shoes with a good grip. Wet pavements and boat decks get slippery, and flip-flops slide easily.
- A dry bag for your phone and passport.
- A light layer for air-conditioned malls, buses and trains.
Plan outdoor sightseeing for the morning and keep indoor options for later in the day. Do not wade or drive through floodwater, and do not shelter under trees in a thunderstorm. If a T-Alert emergency warning appears on your phone, follow its instructions. For the official forecast, call the TMD hotline on 1182.
What to Wear in the Cool Season
Bangkok barely cools down. The average daily high is still 32.3 °C in December, and the average low is 23.2 °C. Summer clothes are fine; add a thin cardigan for cold air conditioning.
Chiang Mai and the north are pleasant by day, with an average high of 29.2 °C in December, but the average low is 16.9 °C in December and 15.7 °C in January. Pack long trousers, a sweater or fleece, and closed shoes for evenings and early starts.
The mountains can be cold. Doi Inthanon, Thailand's highest peak at 2,565 m, had frost for four mornings in a row in late November 2025. On 27 November the summit read 2 °C, and the coldest point on the mountain reached minus 2.3 °C. The park warned that frost can make the summit road slippery. For Doi Inthanon, Phu Kradueng, Phu Ruea or the sea-of-mist viewpoint at Phu Chi Fa in December or January, bring a warm jacket, long trousers, closed shoes, a hat and gloves.
If your trip includes Koh Samui or the Gulf side of the south, keep your rain gear: October to December are the wettest months there.
Dressing for Temples and the Grand Palace
Temples and royal sites expect modest dress. The strictest and best-known code is at the Grand Palace in Bangkok, and following it is a safe choice for any temple visit:
- Shoulders and knees must be covered.
- Not allowed: sleeveless shirts, crop tops, see-through tops, shorts, tight trousers or leggings, miniskirts and torn clothing.
- If you arrive underdressed, you can get a sarong or shawl at the gate. As of September 2026, visitor guides do not agree on whether this is free, so it is easier to arrive already dressed for the visit.
The Grand Palace is open daily from 08:30 to 16:30, but tickets are sold only until 15:30. Admission is 500 THB. Check current details on the Grand Palace website.
An easy temple outfit is loose cotton trousers or a long skirt, a T-shirt with sleeves and comfortable sandals, with a light scarf in your bag. Other temples set their own rules, and some are less strict, but covering your shoulders and knees is always respectful.
Rooftop Bars
Sky Bar at lebua at State Tower in Bangkok asks for smart casual clothes:
- Women: elegant tops, blouses, dresses, skirts, tailored shorts and dress sandals.
- Men: collared shirts, T-shirts, tailored shorts, and loafers or elegant sandals.
- Not allowed: athletic wear, swimwear, sleeveless shirts for men, flip-flops and beach slippers.
- Children: aged 7 and over, with an adult.
Other bars set their own codes, so check the venue's website before you go. The current rules are on the lebua Sky Bar page.
Beaches, Islands and Boat Trips
- Swimwear: wear it only on the beach and at the pool. In town, in shops and in restaurants, put on a shirt and shorts or wrap a sarong over it.
- Sunscreen: since August 2021, Thailand has banned sunscreens containing coral-harmful chemicals, including oxybenzone, in all marine national parks. Fines can reach 100,000 THB. Check the label before a trip to the Similan Islands or Koh Phi Phi.
- Boat days: wear clothes that dry quickly, bring a sun hat, and keep your phone and passport in a dry bag.
Maya Bay on Koh Phi Phi Le reopens on 1 October 2026 after its yearly closure from 1 August to 30 September. The Similan Islands open for the 2026–27 season on 15 October 2026.
Royal Mourning and the December 2026 Royal Cremation
Queen Sirikit The Queen Mother died on 24 October 2025, aged 93. The public was asked to wear black, white or subdued colours for 90 days. That request ended in early 2026, and it was never a rule for visitors.
The royal cremation will take place on 16 December 2026 at Sanam Luang, next to the Grand Palace, within ceremonies from 15 to 19 December 2026. Visitors do not need to wear black, but neutral, modest clothes are respectful during this period. Expect crowds and road closures around Sanam Luang and the Grand Palace, and check before you plan a visit to that area.
Getting Around in Any Weather
Public transport is cheaper, but a private car suits families, travellers with heavy luggage and anyone arriving in a downpour. Smile Taxi Service fares are fixed per vehicle (not per person), one way, with expressway tolls included.
From Suvarnabhumi Airport (BKK) to central Bangkok, the fare is 600 THB by sedan, 800 THB by SUV and 1,100 THB by van. The driver meets you on Level 4 (Departures), near Gate 4. Airport pickups include 60 minutes of free waiting from the actual landing time. You pay the driver in cash (THB) at the end of the trip. If you can only pay by card, message the team for a PayPal payment link; a 5% fee is added. Cancellation is free up to 24 hours before pickup. After that, a cancellation or change costs 25% (less than 24 h), 35% (less than 12 h) or 50% (less than 2 h) of the price, and a no-show 100%, also when you pay the driver in cash (details). Book a sedan from Suvarnabhumi Airport to Bangkok or see all fixed fares.
For a cool-season day in the hills around Chiang Mai, the private Chiang Mai + Doi Tour (up to 10 hours) costs 3,300 THB by sedan, 3,500 THB by SUV, 4,000 THB by van and 4,500 THB by VIP van. See tours and day trips, or read how to get from Bangkok to Chiang Mai.
Frequently Asked Questions
What should I wear to the Grand Palace?
Cover your shoulders and knees. Shorts, sleeveless tops, tight trousers and torn clothes are not allowed. If you arrive underdressed, you can get a sarong or shawl at the gate, but it is easier to arrive already dressed for the visit.
Can I wear shorts to Sky Bar at lebua?
Yes, tailored shorts are allowed. Athletic wear, swimwear, sleeveless shirts for men and flip-flops are not.
Do tourists need to wear black for royal mourning?
No. The 90-day request to wear subdued colours ended in early 2026 and was never a rule for visitors. Neutral, modest clothes are respectful around the royal cremation in December 2026.
Do I need warm clothes for Thailand?
Only for the north and the mountains, from about November to February. Chiang Mai averages 15.7 °C at night in January, and mountain summits can drop below 0 °C.
Not sure what to pack for your dates? Message us on WhatsApp or LINE, or book your transfer online.