The Rainy Season on Koh Chang

Guide to the rainy season on Koh Chang

Visiting the Island between May – October? 

In which case you’re probably wondering ‘What is the rainy season is like?’

May to October is the time of year known as the rainy season.  Or the more welcoming ‘Green season’ if you own a business or are doing marketing for a resort on the island.

Just the term ‘rainy season’ is often enough to deter visitors.  But in reality it shouldn’t be. It doesn’t mean that it will rain all day everyday.  And it’s unlikely you’ll spend your holiday sheltered indoors arguing with your family and wishing you’d booked accommodation with Netflix instead of just the local cable TV. 

In fact, for many visitors the weather is often better than they expected.  That is because if you look at the weather forecasts they will show that it will rain almost day.  But the forecast doesn’t give you the full picture.   

The chances are that it will rain most days.  That is correct. But that could just be a 15 minute downpour in one corner of the island or even very localized rain. For example, it can be bright sunshine in Klong Prao and heavy rain in Kai Bae, just a couple of kilometers away. 

The typical pattern for a rainy season day is that any heavy rain is in overnight downpours or very early morning.  From mid-morning onwards into the evening day it’s likely to be dry and with some sunshine. 

Having said that you could have good luck and get a few consecutive days with not a cloud in the sky. When the weather is like this it’s better than high season.  The sky is very clear, making it ideal for taking photos.  There’s no high season haze.  Colours are brighter.  From the ferry you can look south and see as far as the Cardamom mountains in Cambodia. And the tides are lower, so you’ll get long, wide, deserted beaches to walk on.

Sunny day in the rainy season on Koh Chang

There again, it could be grey and overcast with constant light rain or drizzle for a few days.  Although this is pretty rare.  If you manage to time your holiday to coincide with a few days like this then you have probably upset the travel gods in a previous life. 

One thing to note is that whilst the waves on the sea may not look very intimidating there can often be rip currents at this time of year – even when the weather seems perfect. Many resorts fly red flags when staff know the sea is dangerous.  Many visitors choose to ignore them and play in the waves. Every year people drown.

If you do get caught in a rip current and find yourself being pulled out to sea the #1 thing to do is go with the flow.  You can’t fight against the sea and win.  You’ll get pulled out maybe 50 metres into deeper water.  As rips only occur in a particular location, you can then swim to the left or right of the rip and then head back to shore.  

Rainy season on Koh Chang

If there is a storm then there’s a chance of having a power outage.  Large resorts have generators so their guests aren’t usually affected. But most smaller places don’t. The cause of this is nearly always a tree falling on the power lines.  The electricity will probably be off everywhere south from the site of the incident while the tree is removed and cables are repaired.  Fortunately the guys at the Provincial Electricity Authority are on call 24 hours a day, so even if the power is off late night they will come out and fix it, usually within an hour or two. 

When Does the Rainy Season start?

There isn’t a fixed date for the start or end of the rainy season, but there’s usually a noticeable change in the weather at some point in mid to late May. 

There is always some rain in April but this is more due to the high temperatures and humidity which cause clouds to build up over the hills and result in overnight thunderstorms. 

Heading into May the first couple of weeks are often good, with plenty of sunshine but as the month progresses days will become more overcast and wetter.  Some years it’s as though a switch is thrown. A couple of virtually dry weeks followed by a week of daily torrential rain.  There’s no way to know in advance exactly when in mid to late May sunnier days give way to more cloudier days and the sea will also become rougher. 

Flooding on Koh Chang

When Does the Rainy Season end?

The weather will start to improve during mid to late October.   There’s usually still some rain going into November.  But the worst of the rain should be over by then. 

One key indicator is a change in the direction of the prevailing wind. During the rainy season the winds are blowing off the ocean, from the southwest.  Then one day you wake up and notice that the weather is a little cooler and instead of humid air from the sea, there’s a pleasant, cooling breeze coming from the northeast.  This is drier air coming down from the mainland and China.  Once that occurs it’s just a matter of a week or two before the rainy season will be over. 

In my opinion, November is probably the best month to visit the island.  You get the benefits of high season – trips and tours running, shops and restaurants open, inter-island boats operating & plenty of sunshine.  Plus all that’s good about the low season – clear skies, not too many visitors, lush jungle and waterfalls that are great for cooling off in.  

Travel to Koh Chang, Koh Mak & Koh Kood during the Rainy Season

This is affected by the weather. And also the lack of tourists.  As, aside from the weather being unpredictable, there aren’t enough visitors to make running some boat services viable. 

The ferries to Koh Chang run as normal.  Although there may be longer waiting times for a boat than during high season.  This isn’t so much to do with the weather as it is low tides.  As the main ferry company can’t run all of it’s boats when tides are very low. 

Delays due to severe weather are rare as the strait between the mainland and Koh Chang is sheltered from the prevailing winds.  So, ferry departures due to the weather happen maybe a couple of times a year.  Not for an entire day, just for a 2 or 3 hours when a freak storm passes by.  

Unfortunately inter-island boats between Koh Chang, Koh Mak and Koh Kood don’t operate from early May to mid October.  This doesn’t mean the islands are cut off.  Services still run several times daily from the mainland piers at Laem Ngop, for boats to Koh Mak, and Laem Sok, for boats to Koh Kood. 

This means anyone planning a two or three island holiday will need to also plan for heading back to the mainland and then travelling between piers every time they move from island to island.

Tree down on road on koh Chang

Rainy Season Activities

The majority of activities on Koh Chang are weather dependent. It’s not an island like Samui or Phuket which have shopping malls and a multitude of indoor activities to keep you occupied.

From May to October, the best advice is to plan as normal but build in some flexibility to your scheduling. In particular, allow for last minute cancellations or shifting of days.

Snorkelling and dive trips will run most days. Even if it’s raining.  Of course, if there is a storm forecast or strong waves, boats will remain in harbour.  But on most days it will be possible to take a trip. The boat captains know where the sheltered spots are and although it may not be possible to visit the same islands as in the high season, you will see a lot of fish. 

Just have some flexibility in your plans, there’s no need to plan a specific day for a boat trip a month in advance.  Wait until you are here and see what the weather is like and which services are running. 

As far as jungle trekking and visiting waterfalls are concerned, May to October is a good time to visit.  The jungle will be lush and the waterfalls in full flow.  Of course, the weather plays a part.  Trekking guides wont take people up the hills on very wet days. Or if the trails are too muddy.  It’s supposed to be an enjoyable experience, not a test of your survival skulls. 

During the high season the smaller waterfalls are virtually dry.  But free waterfalls, such as Klong Nonsi, Kai Bae and Khiriphet are great spots to visit for a swim in cold, clear river water during the rain season. Again, have some common sense, don’t swim if the river is in flood. The two main waterfalls, Klong Plu and Than Mayom will close if National Park rangers deem them to be unsafe. 

If you want to see where the locals go for lunch and a swim on sunny, rainy season day, check out Sii Tor River Swimming.  A couple of large, natural pools, ideal for swimming, by a road bridge in the south of Koh Chang, around 2km from Bangbao. There are also usually some foodstalls where you can get BBQ chicken and somtam and a cold coke or beer. 

Kayaking on the ocean is possible on days when the sea is calm.  But conditions can change quickly, so keep an eye out for any grey clouds building up on the horizon or over the hills.  You’ll be surprised how quickly sunshine and calm sea can turn into  a tropical downpour with strong winds. 

A safer option is to paddle inland on the Klong Prao estuary or rent a SUP board at SUP Station adjacent to Iyara Seafood restaurant.  They have guided trips on the river which are possible to virtually every day during the rainy season.

Waterfall in rainy season

A couple of indoor activities that aren’t affected by the weather are taking a cooking class and having a Thai massage.  Keep them in reserve for any days with really bad weather.

Finally, the lack of traffic means that the low season is a good time to explore the island by scooter.  And, as there are far fewer pick up truck taxis on the roads, it’s by far the most convenient and economical way to get around.  On a dry day it’s great.  But on a wet day it can be a nightmare. 

The roads get extremely slippery, especially on the hills in the southwest of the island, from kai Bae to Bangbao. Even experienced riders are caught out.  Bikes can just slip from underneath you, even when riding slowly and carefully. Fortunately most accidents are at low speed and just result in a few scratches and bruises and the rider can pick the bike up and continue. 

The best advice is not to ride when the roads are wet.  And the good news is that they do dry out very quickly.  If it starts to rain and you know you have a hilly section of road ahead just stop and wait. Head for any random cafe or restaurant.  Grab a drink, stay dry and chill for 20 minutes or so until it’s safe to get back on the bike again.

So, Should you Visit Koh Chang During the Low Season?

If you want to be guaranteed a sun tan, then it’s probably not the best time to visit.  Likewise if you have a family with kids that you need to keep occupied and entertained, it’s probably better to head elsewhere.  But if you have some time, don’t have any set plans and enjoy a slower paced vacation, then it’s great time of year to be on the island. 

You’ll find that shopkeepers and business owners who are rushed off their feet in high season now have time to sit to their guests and customers.  People aren’t as stressed and you wont have to wait for a table at your favourite restaurant.

Lush green season jungle Koh Chang

Weather Forecasts and Apps

I’ve played around with a few weather forecast apps and come to the conclusion that is probably the best.  I also know sailors who use this around Koh Chang and confirm that it is as accurate as you will get.  It contains a lot of information including weather radar which seems to work well for short timeframes – say 24 hours in advance. 

The Thai meteorological office supplies most of the data used by all weather apps.  It’s mainly the way that it is interpreted and the amount of additional information that differs.  Their forecast for Trat province is here: