Chiang Mai Weather: When to Visit

Posted by Keith Taylor on September 18th, 2011 in Thailand ~ Comments Off

Chiang Mai Weather

After living in Chiang Mai for a while I began to hear the same few questions over and over again:

What’s the weather like in Chiang Mai?

Is the Chiang Mai weather better than in Bangkok?

When is the best time to visit Chiang Mai?

blah, blah, blah…

But hey, I’m English. By law I’m not allowed to go more than 24 hours without once mentioning the weather.

It’s no surprise that the subject of the weather in Chiang Mai comes up so often for visitors to Thailand, as Chiang Mai weather is.. well, it’s a fickle beast.

Chiang Mai Weather: Lightning

The weather in Thailand, you see, varies widely from region to region. Some areas of the country have a stable climate most of the year (barring the odd tropical storm), but Chiang Mai weather is extremely changeable from season to season. Chiang Mai, in fact, has three distinct seasons throughout the year.

Chiang Mai Weather Seasons

May-November Monsoon

May sees the arrival in Chiang Mai of the south-west monsoon, a weather pattern that brings heavy monsoon rains to the city from May all the way through to November. Throughout this period the Chiang Mai weather is characterised by sudden and often extremely heavy rainfalls that can sometimes cause flooding. The heaviest rain is reserved for September, when each day usually brings at least one downpour.

While this may seem like terrible weather, Chiang Mai is lucky in the sense that this is a typical monsoon climate. Rather than bringing endless dreary showers, the south west monsoon brings brief bursts of heavy rain, often lasting no more than a few minutes (though those few minutes can be enough to get you thoroughly drenched if you’re caught outdoors).

The daily pattern of Chiang Mai weather during the monsoon season is that of clear, dry mornings, cloudy afternoons with heavy rain showers, and dry evenings with the occasional pot of rain. While there’s no way of predicting the exact timing of the showers on any given day, it’s usually possible to escape the wet weather by planning indoor activities during the afternoon. In any case, the heat and humidity can be quite oppressive in the afternoon, so you’ll naturally seek the refuge of air conditioning and cool drinks during rainy periods.

November-May Monsoon

Chiang Mai’s second monsoon season, the north-east monsoon, brings cool, dry air down from China and northern Vietnam. The weather in Chiang Mai during this season is typically much more stable and, arguably, pleasant than the wet season, with warm, clear days, cool nights, very little rainfall and reduced humidity.

The Chiang Mai tourist season kicks off in earnest around November due to the arrival of the pleasant weather. It’s also when the prices will be at their highest, so it’s important to research your trip and plan ahead.

March-May Hot Season

Towards the end of the north-east monsoon the days begin to heat up dramatically, with daytime maximum temperatures often reaching 40 Celsius. This can be an unpleasant time to visit Chiang Mai, as the breeze dies away and the air fills with the smoke from burning vegetation in the countryside surrounding the city.

Chiang Mai Weather – When Should You Visit?

Source - Thai Meteorological Department

As you can see from the table the weather conditions in Chiang Mai vary greatly throughout the year, and if you’re looking for the best time of year to visit I’m afraid it isn’t quite as simple as saying ‘come in April – it’s warm’. Each season has its pros and cons, and it’s up to you to decide when to visit Chiang Mai.

If you’re looking for my advice I’d say the best time to visit Chiang Mai is around January and February. Why? Well, there’s no such thing as ‘perfect’ weather in Chiang Mai – there are always tradeoffs to be considered – but this time of year usually offers the greatest advantages with the least disadvantages.

The temperature often hits 30 degrees Celsius during the day – more than enough for any tourist.

Rainfall is low, and humidity is lower than usual.

The nights are cool and comfortable.

But that isn’t to say that January and February are the only months that offer good weather in Chiang Mai. As I write this I’m sitting on the balcony of my Chiang Mai apartment at the tail end of September, and the weather is beautiful. This is a quick shot from my window at 10AM.

Chiang Mai Weather September

As you can see the weather is lovely. The temperature is around 25 degrees Celsius and there’s a light, cool breeze. If today is like any other September day it’ll remain like this for a few hours, rain for about 20 minutes and then return to glorious sunshine for the rest of the day. Who wouldn’t want to be here?

The Chiang Mai weather is much like this for most of the ‘wet’ season. Rainstorms are brief, sharp and heavy, but as soon as they’re over the sun comes out.

Chiang Mai Weather – When Shouldn’t You Visit?

While most of the year the weather in Chiang Mai is extremely pleasant, there is a brief period during which you should stay away from the city. The reason isn’t entirely to do with the weather, but the stifling heat at the time doesn’t help matters.

March to April Air Pollution

As the average temperature peaks in March and April of each year Chiang Mai experiences an unusual problem. For as long as anyone can remember, rural Thais have burned off undergrowth in the forests of northern Thailand at the beginning of March, and the practice is so widespread that a pall of smoke falls on Chiang Mai for several weeks of each year. Particulates in the air can reach as much as twice the internationally accepted maximum levels, and hospital admission for respiratory illnesses soar at this time of year.

Unfortunately, the location of Chiang Mai in a wide valley amongst the Thai mountains means that every puff of smoke for miles around is funneled directly into the city, where it sits like a fart in an elevator for weeks. The locals deal with this by staying indoors or covering their faces with handkerchiefs, but if you’re visiting a a tourist you won’t want to sit inside all day. It’s best to avoid this time of year – wait until the end of April and the air will be clear once more.

Chiang Mai Weather by Month

January and February

The weather in Chiang Mai is at its most pleasant (i.e. tourist friendly). Temperatures settle at around 25 degrees Celsius, humidity is low, and the evenings are cool and comfortable. At higher elevations the nights can become downright cold, so if you’re visiting the mountains you should bring sweaters and jackets.

March, April and May

The hot season brings blistering temperatures that can send tourists and locals alike scurrying for the comfort of fans and air conditioning. You won’t want to be outside any time around noon, so plan to sit in a cafe with a nice cool drink in the heat of the day. March and the beginning of April can bring unpleasant air pollution.

June, July and August

As the wet season begins the humidity rises and average temperatures fall. It’ll still feel extremely hot even when the temperature is ‘only’ 30 degrees Celsius, and the humidity will see you running through clean shirts faster than you can wash them. The locals fight the humidity by taking three showers a day.

Chiang Mai Sunny Streets

September and October

The tail end of the wet season sees some of the heaviest rainfall of the year, though showers are usually limited to an hour or so. Evening electrical storms can provide entertainment for those who love a good exploding sky.

November and December

The cool dry season brings a welcome break from the humidity, and temperatures begin to fall into the comfortable mid-twenties. Rainfall is rare, humidity is low, and the tourists begin to flock to Chiang Mai once more.

What Clothing Will You Need for the Chiang Mai Weather?

While Chiang Mai is much less humid than Bangkok, the prevailing theme of the city’s weather is unbearable moisture. Unless you hail from a humid climate you’ll find yourself sweating throughout the day and into the night throughout most of the year The key to beating the humidity is light, airy clothing. Chiang Mai is no place for layering of clothes (though you should respect Thai sensibilities and try to avoid showing too much skin). Shorts and t-shirts are the order of the day.

How to Beat the Weather in Chiang Mai

Again, the theme is humidity above all else. You should be drinking plenty of water throughout the day, and if you’re doing anything strenuous you should remember to keep yourself topped up. In a humid climate it’s easy to forget to take on water regularly, considering that you’re covered in a layer of moisture from the moment you step out of your air conditioned hotel.

You should also watch out for sunburn. Chiang Mai is often cloudy during the wet season, but don’t forget that the sun is still blazing away through the clouds. It’s easy to succumb to sunburn even on overcast days, so use an appropriate sunblock and try to stay in the shade.

It can be tempting to save a little money on your accommodation by opting for a fan-cooled room rather than air conditioning, but I’d advise against it. A fan will just recirculate warm, moist air, and in the heat of the day you won’t want to hang around indoors. During much of the year the night time temperature remains high, so you’ll need air conditioning if you plan to get any sleep. Personally, I leave the air con roaring away 25 hours a day (and my electricity bill looks like a phone number).

General Chiang Mai Weather Conditions

In general, the weather in Chiang Mai is cooler than that of the rest of the country. The city’s location in the mountains of the north means lower humidity than southern regions, and the north-east monsoon brings a longer dry season to Chiang Mai than much of the rest of the country.

Chiang Mai Weather: Lightning

For those who are interested in the spectacle, the May-November wet season can bring spectacular electrical storms to the city. I’m no photographer, but I’ve included a couple of lightning shots I managed to grab at the beginning of September from my balcony.

While this talk of torrential rain and oppressive heat may serve to deter you from visiting Chiang Mai, let me put your mind at rest. I am, by far, the most annoyingly wimpy person I know when it comes to extreme weather, and I happily live in Chiang Mai without any problems. I was raised in the UK where I experienced enough depressing drizzle to put me off liquid for a lifetime. Within two weeks of arriving in Chiang Mai during the wet season I had become a die hard fan of water falling from the sky. You see, Chiang Mai weather doesn’t come in half measures. When it rains, it rains.

And it’s fantastic.