The worst times to visit Thailand: What to expect and how to prepare

When are the worst times to visit Thailand?

Pinpointing the worst time to visit Thailand depends on what region you’re visiting and your tolerance for heat and summer storms. Generally speaking, Thailand hosts three tricky seasons — hot season, monsoon season, and burning season in Chiang Mai and its surrounding regions. 

Now, before we get ahead of ourselves, we need to point out that many savvy travelers would rejoice at tackling unpredictable weather in exchange for fewer crowds and cheaper deals — so “worst” may be a bit of a misnomer. Thailand’s hot season and typhoon season combined make up two thirds of the year. Do these unfavorable weather patterns stop folks from exploring this dynamic country for eight months straight? Of course not. You’ll find tourists from around the world partying in Bangkok’s sois and downing cheap Singha on plastic stools year-round. It just means that for many travelers, the months when heavy rainfall and unbearably high temperatures subside is the best time to visit Thailand.¹

So, what makes the “worst times to visit Thailand” unappealing to some vacationers? Let’s examine Thailand’s hottest months, wettest months, and smokiest months in more detail. 

Hottest months in Thailand: March to May 

If you hate cold weather, good news — Thailand is always hot. When we talk about the “hot season,” it’s basically just hotter than the other times of the year, which are … also hot. But even for those who would happily spend their lives in a sauna, the sweltering heat between March and May can be brutal, which is why many travelers consider it the worst time to visit Thailand.

April is typically the hottest month, with average temperatures in Bangkok at 31°C (87°F), often reaching up to 40°C (104°F).

Stepping out of the air-conditioned airport into the bustling streets of Bangkok can only be described as walking in front of a hair dryer. Within minutes, your clothes will be drenched in sweat. Yep, it’s gross, but you’ll have to make your peace with it if you visit Thailand during the hot season. What makes this perhaps the worst time to visit Bangkok is that you won’t get much of an ocean breeze in this dense city. That said, Bangkok offers plenty of air-conditioned malls and restaurants to retreat from the heat. 

Popular spots in Southern Thailand, like Phuket and Krabi, average daily temperatures between 30°C (86°F) to 33°C (91.4°F). But if you’re going to work up a sweat, it may as well be on the shores of the Andaman Sea.

Monsoon season in most of Thailand: June to October 

Hurricanes, cyclones, typhoons, monsoons … whatever you want to call them, they all mean one thing in Thailand — heavy rains. More specifically, the Southwest Monsoon draws moist, warm air from the Indian Ocean and showers most of Thailand — including central and northern Thailand (Bangkok, Ayutthaya, Pattaya, Chiang Mai, and Chiang Rai) and the Andaman Coast (including Phuket and Krabi). The air gets thick with humidity, and dry weather becomes a rarity. From June to October, the country gets seriously soaked, with August and September being the wettest months of the year. 

Crucially, the Gulf Islands in southern Thailand get hit with the rainy season at a slightly different time — from October to December — from the Northeast Monsoon. Keep this in mind if you’re traveling to Koh Samui, Koh Tao, or Koh Phangan. 

But just because it may be hurricane season in Thailand doesn’t guarantee that it’ll rain every day, so, in our humble opinions, it’s not as bad as the country’s hot season. Dare we say that Thailand’s rainy season gets a bad rap? The rain offers an occasional respite from the heat and turns the country into a stunning green paradise — perfect for admiring the jungles up north. 

Burning season in Chiang Mai: February to April 

Tranquil temples nestled in lush jungles. Twinkling golden spires piercing the skyline. A delectable bowl of khao soi over the sound of a local band. Chiang Mai is an absolute must-visit in Northern Thailand … just maybe not between February and April.

This time of year marks the burning season, when agricultural fires are intentionally set by farmers (known as “slash-and-burn” agriculture), leading to dangerously poor air quality across the region. The pollution doesn’t just leave you teary-eyed and short of breath — it also obscures your view of the vibrant blue skies above the foothills of the Himalayas, a view you certainly won’t want to miss. Even locals consider this to be the worst time to visit Chiang Mai, as some leave the region altogether to escape the smoke.

When is the best time to visit Thailand, instead?

November to February is the best time to visit Thailand if you’re looking for great weather and cooler temperatures than the country’s usual scorching months. Winter is the dry season in Thailand, which means no torrential downpours and violent winds — mostly sunny days that won’t have you scrambling for the nearest shelter. 

But you certainly won’t be the only sunseeker — these months are peak season for beach holidays and by default, the most expensive. Temperatures in Phuket and Krabi average around 28°C (82.4°F), perfect for escaping the dreary winters of the northern hemisphere.  

If you’re visiting northern regions of Thailand during peak season, you may even need to pack a jacket for the evening. Temperatures in Chiang Mai can be as low as 15°C (59°F) in December and January. These comfortable temperatures present a great opportunity to stroll around the Chiang Mai Flower Festival to mark Songkran, the Thai New Year. 

Visiting Thailand during monsoon season: What to know

If you’re visiting Thailand from June to October, you’ll be arriving in the middle of the country’s rainy season. Here’s what you should know to prepare for your trip.

Mosquitoes are abundant and they carry diseases

If an award exists for the “worst time to visit Thailand for mosquitoes,” the rainy season would win by a landslide (or more appropriately, a mudslide). As humidity rises, the mosquito population follows. But mosquitoes in Thailand aren’t just a nuisance — they carry serious diseases like dengue fever, Japanese Encephalitis, and malaria. 

Dengue fever — also known as dengue hemorrhagic fever — is not a souvenir you’ll want to bring home from Thailand. Aedes mosquitoes (sometimes called “dengue mosquitoes”) have become an increasing problem over recent years, as the Thailand Bureau of Epidemiology reported a 123% increase in dengue fever cases from 2023 to 2024.²  These mosquitoes thrive in areas with heavy rainfall, dense forest, and persistent cloud cover — all features that make areas of northern Thailand, particularly Chiang Mai, simultaneously enchanting and a bit risky.^3,4 

The good news? Vaccines exist for all three diseases. The bad news? Depending on where you’re from, they can be pricey — and you’ll most likely have to pay out of pocket. That said, investing in a strong mosquito repellant and staying away from dense forests during the rainy season will reduce your risk. 

Flooding in Bangkok can be serious — and dangerous

As the effects of climate change ramp up, so does flooding in Bangkok — particularly during the wet season.⁵ Streets can quickly turn into rivers, and while wading through ankle-deep water in search of the best night market might sound adventurous, you can’t always see what’s floating beneath the surface. Encountering sharp debris or uneven pavement can spoil an evening outing. 

Another danger during the rainy season in Bangkok is the live wires hanging above sidewalks. If you’ve ever seen photos of the city’s tangled web of power lines, you know what we’re talking about. Electrocution isn’t an everyday occurrence, but it is possible — and hearing the crackle of sparking wires overhead is enough to send you sprinting back indoors. 

Your beach holiday may not go as planned

The west coast of southern Thailand, home to Phuket, gets plenty of rainy days from late May to October (with the most rainfall in September and October).  The waves of the Andaman Sea tend to be rougher during this time, which means choppy waters, potentially dangerous swimming conditions, and limited visibility for scuba diving after storms. You may even miss out on those iconic longtail boat rides quintessential to the Thai beach experience. 

Tips for monsoon season in Thailand

If you’re traveling to Thailand from June to October, here’s how you can prepare for the country’s rainy season:

• Get vaccinated against dengue fever, Japanese encephalitis, and malaria, if you can. Travel vaccines can be pricey and are often paid out of pocket, but may just be worth it if you’re heading into mosquito-ridden regions of the country. 

• Buy health insurance. Rain or shine, this is a good move any time you travel to Thailand. Even if it’s just a case of Bangkok belly that lands you in a local clinic, it’s best to be covered for any health emergencies — whether mosquito-related or not.

• Use mosquito repellent. The stronger, the better. If you’re bringing it in your carry-on, just make sure it’s 100 ml or less.

• Consider investing in mosquito-resistant hiking pants. This will especially come in handy if you’re visiting the jungle regions of northern Thailand.

• Keep your plans flexible. Don’t get too attached to your itinerary during the rainy season — outdoor adventures might have to be swapped with museum visits instead. 

• Bring waterproof shoes with good grip. Slick sidewalks are prevalent in city centers. Better to be safe than sorry!

Tips for surviving the hot season in Thailand

March to May’s temperatures are no joke, and heat exhaustion is a serious risk. If you’re planning to visit Thailand during the hot season: 

• Stay hydrated. You’ll be sweating a lot during the hot season. Stock up on water and electrolyte drinks. 

• Prioritize sightseeing in the early morning and evening. Take it easy while the scorching midday sun is out. 

• Wear breathable, loose-fitting clothing. You will see locals wearing full denim in this weather — don’t try to match their energy. Heat exhaustion is real, and your body will not thank you for it. Just keep in mind not all summer clothes may be appropriate according to Thai customs, especially when visiting temples. Be respectful of local customs while staying comfortable. 

• Rest when you feel like you need to. You may be on a once-in-a-lifetime trip, but scrambling to see and do everything shouldn’t be prioritized over your health. 

Stay connected in Thailand with an eSIM

Whether you’re updating mom on your adventures or finding directions to the closest night market, you’ll likely want internet access while traveling around Thailand — which is made easy with an eSIM. 

A roaming bill can put more of a damper on your trip than the rainy season, and searching for a physical SIM card is a waste of time that could be spent exploring. Instead, you can get affordable mobile data plans by downloading the Saily eSIM app and enjoy reliable internet access with an eSIM for Thailand!

The worst times to visit Thailand: Final takeaways

Still not sure when to book your trip to Thailand? Here’s a final breakdown of the worst times to visit Thailand: 

• Thailand is a year-round destination, but if you’re planning a beach holiday, the worst time to visit is during typhoon season (June to October). If you’re sticking to cities, the worst time to visit is the hot season (March to May). The worst time to visit Chiang Mai is during the burning season (February to April). That leaves us with November to March, which is overall the best time to visit Thailand for pleasant weather.  

• Weather patterns vary slightly between the east coast and the rest of the country, where the rainy season arrives slightly later in the year. If you’re visiting islands like Koh Samui, Koh Tao, or Koh Phangan, October and December are stormiest. 

• Rain isn’t guaranteed every day during the wet season, but heat is pretty much guaranteed every day during the hot season. 

The rainy season presents challenges like flooding, increased mosquitoes, and dangerous swimming conditions in the Andaman Sea.

References

¹ Bank of Thailand. (2025, March 31). EC_EI_028_S2 Tourism indicators. https://app.bot.or.th/BTWS_STAT/statistics/ReportPage.aspx?reportID=875&language=eng

² The Government of the Hong Kong Special Administrative Region, Department of Health. (2024, April 29). Travel health news. https://www.travelhealth.gov.hk/english/outbreaknews/2024/ond23April2024.html

³ Kaewhan, S., Junpha, J. & Pimpeach, W. (2025, January 19). The regional distribution of dengue fever in Thailand and other emerging countries in Southeast Asia: A literature review. Toxicology and Environmental Health Sciences. https://doi.org/10.1007/s13530-025-00251-1

⁴ Abdulsalam, F. I., Antunez, P., Yimthiang, S., & Jawjit, W. (2022, April 20). Influence of climate variables on dengue fever occurrence in the southern region of Thailand. PLOS Global Public Health 2(4). https://doi.org/10.1371/journal.pgph.0000188

⁵ Worawiwat, A. & Chaleeraktrakoon, C. (2024, September 1). Is the rate of extremely climate-intensifying rainfall for Bangkok severely propagating into flooding? Journal of Water and Climate Change, 15(9), 4405-4417. https://doi.org/10.2166/wcc.2024.106