Thailand Weather: Seasons, Monthly Climate, and Best Times to Visit
Thailand weather is warm year-round, but the experience changes with the monsoons that shape three clear travel seasons. Understanding how winds affect each coast helps you choose the right month and region, whether you are planning beach time, city sightseeing, or trekking. This guide explains seasons, regional differences, and Thailand weather by month so you can match your plans to calmer seas and comfortable temperatures.
Thailand weather at a glance
Thailand’s climate is tropical, with warm temperatures, high humidity, and pronounced wet and dry phases driven by seasonal winds. Conditions vary by coast, elevation, and latitude, so Phuket and Koh Samui can have different rain patterns on the same week, and mountain mornings in the north can feel cool while Bangkok stays warm overnight. This section offers quick facts that help set your expectations before you dive into regional and monthly detail.
Quick facts: temperatures, humidity, and rain patterns
Across most lowland areas, typical daily temperatures run from about 24–35°C throughout the year. April often feels hottest, while December–January bring the most comfortable mornings, especially in the north. Humidity is frequently 60–85%, which makes the “feels-like” temperature several degrees higher than the air temperature in the hot and rainy seasons. On a 33°C day with high humidity and light wind, it can feel closer to 38–40°C during mid-afternoon.
Rain in the wet season usually arrives in short, intense bursts that last 30–90 minutes, often in the afternoon or evening, followed by sunny intervals. Prolonged rain systems are less common but can occur, especially near seasonal peaks. UV levels are high even on cloudy days, and sea breezes can make coasts feel more comfortable than inland cities. Microclimates are real: the lee side of an island can be dry while the windward side has showers, and higher elevations are cooler with faster-changing conditions.
- Typical lows and highs: roughly 24–35°C in lowlands; cooler at elevation
- Humidity: usually 60–85%; driest air November–February
- Rain pattern: brief, heavy showers with sunny breaks; occasional multi-day rain near peaks
- UV index: strong year-round; sun protection is needed in all seasons
- Local variation: coast, island aspect, and elevation create microclimates
How monsoons shape the three seasons
A monsoon is a seasonal wind pattern that shifts moisture and storm tracks; it does not mean constant all-day rain. From about May to October, the southwest monsoon brings moisture from the Indian Ocean, increasing rainfall across most regions and especially along the Andaman coast. From November to February, the northeast monsoon reverses the flow. Much of Thailand becomes drier in this period, while the central Gulf, including Koh Samui, Koh Phangan, and Koh Tao, can see late-year rains as moist air moves across the Gulf of Thailand.
These wind-driven patterns create three traveler-facing seasons: the cool/dry season (roughly November–February), the hot season (March–May), and the rainy season (May–October). Timing can shift by a few weeks depending on the year, local sea temperatures, and geography. Understanding this split helps you pick the right coast for your month of travel.
Thailand seasons explained
Thailand’s three seasons affect humidity, visibility, sea state, and comfort levels in different ways. Each has advantages depending on your priorities, from calmer seas and clear skies to lush landscapes and lower prices. The following sub-sections describe what to expect and how to plan, including regional exceptions that matter for real-world itineraries.
Cool/dry season (Nov–Feb): where and why it is best for travel
From November to February, lower humidity, clearer skies, and more stable conditions make travel comfortable across most regions. The Andaman Sea is typically calm from December to March, which favors swimming, island-hopping, and dive visibility. Bangkok and the central plains feel most pleasant in December–January, while the northern highlands enjoy cool mornings and warm, bright days that are ideal for trekking and outdoor markets. Koh Samui improves quickly from January as late-year Gulf showers fade.
There are still local nuances. The central Gulf, including Koh Samui, can experience occasional late showers in November and into early December, before drying out. In the far north and in highland national parks, cold snaps during December–January can drop night and early-morning temperatures low enough to need a sweater, light jacket, or mid-layer. Because this is the most popular period, demand surges around late December to early January, with peak pricing and limited availability for ferries, flights, and beach resorts. Book key legs early if your dates fall during holiday weeks.
Hot season (Mar–May): heat management and sunshine hours
The hot season brings abundant sunshine and long, bright days leading up to the monsoon onset. Temperatures and the heat index peak in April. The difference between the air temperature and what your body feels can be significant; for example, 35°C with high humidity and weak wind can feel like 40°C or more. Coastal breezes moderate the heat on islands, while inland cities such as Bangkok and Ayutthaya feel hottest from mid-afternoon until early evening. Nights remain warm, especially in urban areas where heat lingers.
Schedule outdoor sightseeing, runs, and hikes for early morning or late afternoon, and use midday for shaded cafes, museums, or transit. Hydrate frequently, seek shade, and wear breathable fabrics. A brimmed hat, sunglasses, and high-SPF sunscreen reduce sun stress. On the coasts, mornings are often calmest, offering the best windows for snorkeling and boat transfers before afternoon winds freshen.
Rainy season (May–Oct): rainfall peaks and travel advantages
May to October is the green season for much of Thailand. Showers are usually brief but heavy, with many days shaped by a sunny morning, a moody buildup, and a late-day downpour. The Andaman coast tends to see its peak rainfall in August–September, along with stronger waves and more frequent surf. The central Gulf is often more settled during mid-year, which can make Koh Samui, Koh Phangan, and Koh Tao attractive in July–August compared with west-facing beaches.
It is useful to distinguish between localized convective storms, which pass quickly, and broader weather systems that can deliver multi-day rain. Low-lying urban areas can experience short-term street flooding near peak months, so allow buffer time in schedules and consider flexible bookings. In exchange, you get dramatic skies, greener landscapes, and fewer crowds. With a bit of flexibility, rainy-season travel offers strong value, especially for inland cultural trips and rainforest parks that come alive under frequent showers.
Regional weather by destination
Thailand’s regions differ in rainfall timing, sea states, and daily comfort. The Andaman coast follows one pattern, while the central Gulf follows another. Bangkok’s urban heat contrasts with the cooler northern highlands. These distinctions matter for practical planning, from ferry reliability to trekking comfort. The following summaries align the seasonal picture with well-known destinations so you can choose the right place for your month of travel.
Bangkok and Central Thailand
Bangkok and the central plains are hot and humid most of the year. The driest window is usually December–February, when humidity drops and mornings feel more comfortable. April is typically the hottest month, with high heat index values and warm nights. From May to October, frequent afternoon and evening thunderstorms are common, delivering short, intense rain that clears the air for a time. Urban heat island effects keep nighttime temperatures elevated, and air quality can vary during stagnant dry spells.
Plan activities to match the climate. Schedule outdoor walks by the Chao Phraya River or in historic districts for early morning or late afternoon, and save indoor highlights such as museums, malls, or cafes for midday. Keep a compact umbrella or poncho handy from May to October. If you are researching “weather in Thailand Bangkok” for specific months, note that December–January offer the most comfortable conditions for temple visits and rooftop views, while April requires extra hydration and shade breaks between sights.
Northern Thailand (Chiang Mai, Chiang Rai)
Northern Thailand enjoys cooler nights and pleasant days during November–January. In city valleys such as Chiang Mai, mornings can dip near 10–18°C, with crisp air and strong sunshine by late morning; at elevation, it can feel markedly colder, especially before sunrise. Trekking, cycling, and outdoor markets are most comfortable in the cool/dry months. The wet season from May–October brings lush rice terraces, fuller waterfalls, and clean air after showers.
From late February to April, some areas experience seasonal haze that reduces visibility and can affect sensitive travelers. Check local conditions if you plan viewpoints or long treks in this period. Pack differently for mountains and cities: a light sweater or fleece for cool mornings and nights, and breathable layers and sun protection for warm afternoons. Footwear with grip helps on damp forest trails in the green season, when leeches are more active in some parks and simple leech socks can be useful.
Andaman Coast (Phuket, Krabi, Phi Phi, Lanta)
The Andaman coast is at its best for beach holidays from December to March. Seas are calmer, visibility is clearer, and marine excursions run reliably. The rainy season spans roughly May–October, with the strongest waves and rip currents often from July to September. While many days still feature sunshine between showers, surf can limit swimming on west-facing beaches and visibility for snorkeling can decrease.
Safety and logistics deserve attention. Some marine areas, such as the Similan Islands, operate seasonally with peak windows in the dry months. If seas are up, consider sheltered east-coast beaches on Phuket for calmer water.
Gulf Islands (Koh Samui, Koh Phangan, Koh Tao)
The central Gulf typically enjoys its driest, sunniest stretch from January to April, making it a strong choice for early-year beach trips. Late-year rains peak from about October to early December during the northeast monsoon. Mid-year, especially June–August, often brings more settled conditions compared with the Andaman side, which is why many travelers choose Samui or Koh Tao in July–August.
Wind and swell direction affect snorkeling and dive visibility. On Koh Tao, visibility can be excellent in mid-year when winds are favorable, while late-year swells may reduce clarity on some sites. Microclimates exist on Samui; depending on wind direction, the north and northeast coasts can be slightly drier than the windward side. When planning island-hopping, check marine forecasts and consider basing near harbors to adapt quickly if conditions change.
Eastern Gulf (Pattaya, Rayong, Koh Chang area)
Koh Chang sees its wettest period in September–October, and hilly terrain channels runoff, creating dramatic waterfalls in the green season. Beach conditions vary with local wind and swell; on changeable days, sheltered bays around Koh Samet or Koh Chang’s leeward pockets can provide calmer water.
Proximity to Bangkok brings busy weekends in fair weather, so plan transport with buffers. Ferry schedules to Koh Chang and surrounding islands can shift during heavy weather; check updates the day before travel and allow extra time for transfers from the mainland. On showery days, combine short beach windows with inland attractions and cafes, saving longer sea excursions for clearer forecasts.
Monthly weather overview (quick-reference table)
Many travelers search for Thailand weather by month to pinpoint the best weeks for beaches, city trips, or trekking. While long-term averages are consistent, each year can vary by a few weeks depending on regional wind shifts and sea temperatures. Use the table below to compare typical temperatures and rainfall tendencies for Bangkok and Central Thailand, Northern Thailand, the Andaman coast, and the central Gulf.
Remember that these are broad patterns rather than specific daily forecasts. For example, Thailand weather in November is usually dry and comfortable in most regions but can still bring late showers around Koh Samui; Thailand weather in December is excellent on the Andaman; Thailand weather in October leans wetter on the Andaman but begins improving in the north; and Thailand weather in August is often peak rainy on the Andaman yet relatively steady on the central Gulf. Always allow a margin for changeable days.
Best and rainiest months at a glance
Generally best overall months for comfortable travel are November–February, with Andaman beaches peaking December–March and the central Gulf peaking January–April. The rainiest periods tend to be August–September for the Andaman and October–November into early December for the central Gulf. Bangkok is most comfortable December–January; the north is cooler November–January with chilly mornings. Ranges below are typical averages rather than guarantees.
Use this quick-reference to match plans with seasonal strengths. Divers may time Similan liveaboards for mid-dry season, while families seeking calm seas in July–August often pick Koh Samui. City travelers who want cooler air target December–January, and hikers consider November–February for clear skies and long views. Year-to-year variability occurs, and microclimates can alter conditions locally.
| Month | Bangkok / Central | Northern Thailand | Andaman Coast (Phuket, Krabi) | Central Gulf (Samui, Phangan, Tao) | Jan | 24–32°C; generally dry, low humidity | 14–29°C; cool mornings, sunny days | 27–32°C; calm seas, dry | 27–31°C; mostly dry, improving visibility | Feb | 25–33°C; dry, comfortable mornings | 15–32°C; crisp mornings, ideal trekking | 27–33°C; calm, clear; beach peak | 27–32°C; dry and sunny | Mar | 27–34°C; hotter, still relatively dry | 18–34°C; warming, dry | 28–33°C; mostly calm; occasional haze | 28–33°C; dry; excellent beach time | Apr | 28–36°C; peak heat, strong sun | 22–36°C; hot afternoons | 28–33°C; hotter; pre-monsoon showers possible | 28–33°C; sunny; heat moderated by breezes | May | 27–34°C; start of rainy season; afternoon storms | 23–34°C; first rains, greener hills | 27–32°C; rainy season begins; waves build | 28–32°C; mixed; often manageable seas | Jun | 27–33°C; frequent showers | 23–33°C; regular rain, lush scenery | 27–31°C; unsettled; rougher surf | 27–31°C; relatively settled mid-year | Jul | 27–33°C; wet afternoons, sunny breaks | 23–32°C; green and fresh | 27–31°C; wettest stretch begins; strong waves | 27–31°C; good option vs Andaman | Aug | 27–33°C; wet; flood-prone spells possible | 23–32°C; frequent showers | 27–31°C; peak rain; rough seas | 27–31°C; often steady, good diving windows | Sep | 26–32°C; wet; heavy bursts | 23–31°C; rainy; waterfalls strongest | 26–30°C; peak rain persists; rip currents | 27–30°C; mixed; some sunny days | Oct | 26–32°C; transition; frequent storms | 22–31°C; improving late month | 26–30°C; very wet; surf strong | 27–30°C; rain increases; swell rises | Nov | 25–32°C; drying; pleasant | 18–30°C; cool/dry returns | 27–31°C; improving; good by late month | 26–30°C; rainiest period begins | Dec | 24–32°C; dry, comfortable | 15–29°C; cool mornings | 27–32°C; peak beach weather | 26–30°C; showery early month, better late |
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Best times to visit Thailand
The best time depends on your trip style and the regions you plan to visit. Beaches thrive when seas are calm; cities feel best when humidity is lowest; and rainforests shine during the green season. Use the guidance below to match your priorities with the right coast and month, from family trips to dive holidays and romantic escapes.
Beaches and islands
For classic beach weather, the Andaman side is most reliable December–March, while the central Gulf shines January–April. Families who want gentle seas and reliable ferries often choose Phuket, Krabi, or Khao Lak from December to March, and Koh Samui from January to April. July–August can be a smart mid-year choice on the Gulf if you remain flexible and accept a mix of sunny spells and showers.
Surfers find their season on west-facing Andaman beaches during the rainy months when waves are up, while divers target dry season windows for the best visibility on both coasts. Honeymooners seeking tranquility can look at shoulder periods such as late November or late April for value and good odds of fair weather. Match destinations to sea conditions for swimming, snorkeling, and ferry reliability, and avoid swimming during red-flag conditions.
Cities and cultural trips
Bangkok and the central plains are most comfortable December–February, when humidity drops and mornings feel fresher for temple visits, walking tours, and rooftop views.
Plan museum and temple interiors for midday, and explore outdoor markets in the early morning or evening. Dress for both climate and culture: breathable tops that cover shoulders, light trousers or long skirts that cover knees, and easy-on shoes for temple entries. Carry water and electrolyte tabs in the hot season, and pack a compact umbrella or poncho for May–October showers.
Nature, trekking, and national parks
Northern treks are most comfortable in the cool/dry season from November to February, when skies are clear and temperatures suit long hikes. Green-season trekking from June to October rewards with lush forests and strong waterfalls, especially in parks like Doi Inthanon, Doi Suthep-Pui, and Huai Nam Dang.
In rainforest regions such as Khao Sok, the green season enhances wildlife sounds, river levels, and misty mornings. Some trails close during heavy rain for safety, and leech activity increases on damp paths; bring leech socks if you plan multi-day hikes. For remote areas, check permit rules, consider local guides, and watch storm forecasts before committing to river crossings or ridge routes.
Packing and planning tips by season
Smart packing and a flexible daily plan help you enjoy each season. The aim is to stay sun-safe, dry during showers, and respectful at cultural sites while keeping cool. The following tips cover core items and scheduling strategies that work across Thailand’s varied regions and months.
Essentials for cool/dry, hot, and rainy periods
Pack light, breathable clothing that dries fast. Include sun protection such as a wide-brim hat, UV-rated sunglasses, and high-SPF, reef-safe sunscreen. Insect repellent is useful year-round, especially near dusk. A light rain jacket or poncho and a compact umbrella help in the wet season. Dry bags protect phones and cameras during boat trips and sudden showers, and quick-drying layers keep you comfortable between bursts of rain.
Footwear matters: closed-toe shoes or sandals with grip handle wet paths, temple stairs, and slick piers. Add a warmer layer for cool northern nights in December–January. For temple etiquette, bring modest, breathable options: tops that cover shoulders and long pants or skirts that cover knees, made of light fabrics such as linen or moisture-wicking blends. A thin scarf can double as sun cover and temple wrap.
- Breathable tops, long trousers/skirts for temples
- High-SPF reef-safe sunscreen and sunglasses
- Insect repellent; small first-aid kit
- Light rain jacket/poncho; compact umbrella; dry bags
- Sturdy sandals or shoes with grip; light warm layer for the north
Daily planning: timing activities around heat and showers
Plan outdoor activities for early morning and late afternoon when temperatures and UV exposure are lower. Use midday for rest, transit, or indoor sights. In the wet season, mornings are often the best window for boat trips and hikes before convective clouds build. Add buffer days when your itinerary includes island transfers, and try to align long ferry crossings with the calmest forecast period.
Check marine and weather forecasts daily. The Thai Meteorological Department provides reliable updates, and marine bulletins from port authorities and local operators help with sea-state decisions. When reading rain probabilities, think in terms of “chance of one or more showers” rather than continuous rain. Observe lightning safety: if thunder is audible, seek shelter indoors and avoid open water, beaches during storms, and hilltops until 30 minutes after the last thunder.
Rainy-season travel: practical tips
Traveling in the green season can be rewarding if you stay flexible. Coast-switching, weather buffers, and cautious sea choices help you find sunshine and keep your schedule intact. The notes below show how to pivot between the Andaman and Gulf coasts and how to manage sea and transport safety when conditions change.
Coast-switching and flexibility
When the Andaman is wet from May to October, consider the central Gulf. When the Gulf is wet from roughly October to early December, consider the Andaman. Flexible bookings let you pivot if forecasts shift. Basing in transport hubs such as Phuket, Krabi, Surat Thani, or Koh Samui allows quick adjustments to island plans as weather evolves.
Plan inter-coast travel using nearby airports and realistic transit times. Common route pairs include HKT (Phuket) to USM (Koh Samui) via a short flight connection, KBV (Krabi) to URT (Surat Thani) by road in 2.5–3.5 hours, or Phuket to Khao Lak in 1.5–2 hours by road. Allow extra time for ferry check-ins and potential weather delays, especially during July–September on the Andaman and October–November on the Gulf.
Sea conditions, safety, and transport notes
Rip currents and large surf are common on west-facing beaches in the rainy season. Always follow beach flags and lifeguard advice, and avoid swimming under red flags. Be cautious on piers and wet rocks, which can be slippery. If seas are rough, choose sheltered bays, switch to inland activities, or postpone crossings to the next calm window.
Ferry and speedboat schedules can change with weather. Monitor operator updates and consider travel insurance that covers weather-related disruptions. Diving seasons and liveaboards vary by region; for example, some Andaman parks operate mainly in the dry months, while Koh Tao diving is often favorable mid-year. Verify seasonal windows and expected visibility with operators before booking.
Frequently Asked Questions
What are the best months to visit Thailand for good weather?
November to February offers the most reliable dry, cooler conditions across much of Thailand. Beaches are typically best from December to March on the Andaman side and January to April on the central Gulf. These months have lower humidity and calmer seas. Book early for December–January peak demand.
When is the rainy season in Thailand and how heavy is the rain?
The main rainy season runs from May to October for most regions, peaking in August–September. Showers are often short, intense, and followed by sunny breaks, though multi-day rain is possible in some areas. The central Gulf (Koh Samui area) sees its heaviest rains in October to early December. Rainfall intensity varies by coast and elevation.
Is December a good time to visit Thailand’s beaches?
Yes, December is excellent on the Andaman coast (Phuket, Krabi, Phi Phi, Lanta) with dry weather and calm seas. The central Gulf (Koh Samui) is improving but can still see late-monsoon showers early in the month. Expect high demand and higher prices during the Christmas–New Year period.
What is the weather like in Bangkok in April?
April is typically the hottest month in Bangkok with daytime highs around 34–38°C and warm nights near 27–28°C. Humidity is high, and sunshine is abundant before the monsoon arrives. Plan indoor activities at midday and hydrate frequently. Songkran (mid-April) coincides with peak heat.
Does Phuket have good weather in July and August?
July and August are in Phuket’s rainy season with frequent showers and stronger waves. Many days still have sunny windows, but seas are often rough, and red flags are common. It is a good time for value and fewer crowds if you accept changeable weather. Always follow local beach safety guidance.
When is the rainy season on Koh Samui?
Koh Samui’s heaviest rains usually occur from October to early December due to the late-year Gulf monsoon. January to April is generally the driest period with good beach conditions. Warm temperatures persist year-round. Local microclimates can make the north and northeast slightly drier.
Which Thai regions are cooler during the dry season?
Northern highlands (Chiang Mai, Chiang Rai) are cooler from November to January, especially at night and at elevation. Daytime conditions are pleasant for outdoor activities, with chilly mornings possible in December–January. Coastal areas remain warm but less humid than in the wet season.
Is it worth visiting Thailand in the rainy season?
Yes, the rainy season brings lower prices, fewer crowds, and lush landscapes. Showers are often brief, leaving clear periods for sightseeing. Plan flexible schedules and consider coast-switching to find more sunshine. Wildlife and rainforest experiences (e.g., Khao Sok) can be excellent.
Conclusion and next steps
Thailand weather follows a clear rhythm shaped by the southwest and northeast monsoons, yet each coast, city, and mountain zone has its own microclimate. For beach reliability, the Andaman coast peaks December–March and the central Gulf peaks January–April. Cities are most comfortable in December–February, while northern highlands offer cool mornings in the dry season and lush scenery in the green season. The rainy months still deliver many sunny windows, with the added benefits of vibrant landscapes and fewer crowds.
Plan around heat and showers by prioritizing mornings and late afternoons for outdoor activities, adding buffers for island transfers, and checking local forecasts. Match your destinations to the month: consider Koh Samui in July–August when the Andaman is wet, and pivot back to the Andaman in December when the Gulf can be showery. With flexible expectations and smart packing, Thailand’s seasons can each deliver a rewarding trip, whether your focus is beaches, cultural cities, or nature-rich national parks.
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