Koh Samui
August 4, 2023

Koh Samui in September: What to expect

My verdict? Koh Samui in September is a genius move. Here's everything you can look forward to, what to expect, what to pack and more.

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Koh Samui in September

A September afternoon at SALA Samui Chaweng Beach Resort

Don’t tell Santa (or Songkran) but September is one of my favourite months on Koh Samui. Here’s what to know, and what to do.

Koh Samui questions? Start here

The Koh Samui Guide: Arrive better prepared, and get exploring right away. Find everything you want to do (and want to see, try, taste or buy) in The Koh Samui Guide. You’ll see more of the good stuff, and avoid the rest.

Where to stay in September

My pick: SALA Samui Chaweng Beach Resort

SALA Samui Chaweng Beach Resort

I think this resort stands out as a superb spot for couples and why not enjoy it best when you've practically got the island to yourself? Choose between rooms or pool villas on the ocean side or the garden side of the resort. (The latter offers a little more shade)

See Rates + Details

Hotel Tip: On Chaweng Beach you’ll find a great range of options, including resorts with private pool villas, boutique choices and more. For details on enjoying Chaweng as an introvert, extrovert, parent or partier, don’t miss the detailed beach guides and comparisons in The Koh Samui Guide.

More hotel ideas

Hotel questions? Start here

Looking for something specific? Perhaps you want to sleep in a shipping container? Or you desperately need an Olympic sized swimming pool? Look no further. For an introduction to Koh Samui’s beaches and great hotel suggestions, start here:

What to pack for September

1. Mosquito Repellent Wristbands

Mosquito-repelling bracelets are especially clever in Thailand when you’ll sweat off a repellent spray and be left vulnerable. Also, they’re natural and DEET-free. (You know how I feel about beagles and bunnies). For top to bottom (really, don’t forget your bottom) tips, see how to avoid mosquitoes in Thailand. You’ll learn your choices for natural vs DEET repellents, plus discover dozens of clever repellent accessories and travel products.

2. The Rough Guide to Thailand

Brand new and totally updated. This new guidebook offers thorough Thailand coverage with particular attention given to Bangkok. Itineraries and colour-coded maps are an easy starting point (though for Koh Samui you'll want The Koh Samui Guide).

3. Thailand Travel Adapter

If it’s been a while since you travelled overseas, don’t forget adapters. As a quick refresher, Thailand uses the same plugs as the U.S. and Canada (plug types A and B, two flat pins parallel to each other and two flat pins with a round ground pin) and also plug types C and F with two round pins (common in Europe).

4. Supergoop! Unseen Sunscreen

This is my favourite face sunscreen for Thailand (and I've tried everything). It goes on clear and stays invisible. (Avoid anything with a tint as it will sweat straight off on to your nice white linen shirt). For men? It applies easily on to stubble or beards, with no white smeared stuff.

What to wear on Koh Samui in September?

Even if it's cloudy, don't forget about Koh Samui's incredible levels of UV (just 660 miles from the equator). Year-round, its indexed UV rarely drops below 11, 12 or 13 (extreme and more extreme). For reference, London is typically 5 or 6 in high summer). What does this mean in wearable terms? Start with a quality sunscreen of SPF30 or higher and set a timer on your phone to reapply it every few hours if you're in the sun for a period. Add generous cover-ups and sunhats too. No wrinkles for you!

Packing questions? Start here

Weather in September

Starting the month right: September 1st at Melati Beach Resort

September averages

  • Temperature: 28°C / 82°F
  • Sunshine (hours/day): 6
  • Rainy days: 11 days (130 mm / 5 inches)
  • Sea temperature: 28°C / 82°F

What’s the weather like on Koh Samui in September?

Compared to other months of Koh Samui’s climate, where major heat/rain/clouds can feature, Samui in September offers truly gorgeous weather. Coming at this time of year, you have a wide margin of weather-safety until clouds, wind and rainy season arrives sometime in October. My verdict? Koh Samui in September is a genius move, especially so in the first half in the month.

Hansar Samui in September

Is it sunny on Koh Samui in September?

September can be cloudy or overcast, with those odds increasing over the course of the month. The same goes for the chance of rain. However, I think it's a Goldilocks "just right" month where you're assured balmy temperatures, slight breezes, and a decent chunk of sunshine. There's nothing in a 'statistically accurate' September that should warn you off a visit. On the contrary, we've established there will be few small children around your hotel pool: start packing.

How much does it rain on Koh Samui in September?

Statisticaly, September is not considered a "rainy" month. Should you spot rain on the forecast, don't worry. Thailand has fantastic rainstorms; enjoy them best with a good book or a family travel game (and a Singha or coconut shake sourced nearby).

A stormy afternoon – mid September on Chaweng Beach

How hot is it on Koh Samui in September?

Back to averages: 28°C (82°F) is your standard issue September starter pack. A hot day can reach 31°C (88°F) and an unseasonable cold snap might drop to 25°C (77°F). This would be big news and you'd probably see Thai people in sweaters.

In this tropical climate, it's always useful to remember the humidity level or Humidex which gives you a much better sense of how you'll feel in a given temperature. September is classified as "muggy" for all 30 days but less so than August or October.

If this is a lot of data, perhaps picture an easier reality: beach bed, gin and tonic, brand new book. September is superb.

Is it rainy season in September?

No, it's a wonderful shoulder month before October tends to get a bit cloudier with slightly stronger wind. November will usually be the main rain event.

September events calendar

Early September on Choeng Mon Beach

September 2023 events

Your September FAQs

The Koh Samui Guide

What are the best things to do on Koh Samui in September?

In previous years, Koh Samui has hosted lots of sporty events in September including a hill challenge running race and an island adventure race. Whether such events or others like them appear on this year’s calendar remains to be seen (Koh Samui tends to be an 11th hour kind of place – check the calendar for updates).

Of course, if you have no interest in athletic pursuits, trust me, that is not going to be a problem.

A few, fairly lazy activity suggestions for September on Koh Samui? Above all, it’s an ideal time to visit Angthong Marine Park – so be sure to set aside a full day. Besides, that, stretch out and enjoy some yoga on Samui. Take a Thai cooking course – or learn to sail. Spend hours on a beach, with a great beach book. And definitely, spoil yourself (and your special friend) at Samui’s spas.

The Koh Samui Guide: Instead of allowing yourself to get weather-obsessed, I recommend you book your Koh Samui vacation when it’s most convenient, when you most need days of perfect relaxation. Rest assured if it does decide to pour‚ any day of the year‚ there’s still plenty to do (rain or shine The Koh Samui Guide will easily keep you busy).

What are the beaches like on Koh Samui in September?

Empty! I can’t emphasize enough the difference between busy late August and just as beautiful but ‘desert island’ early and mid September.

Ogling from above – Chaweng Beach in September

Which beach is best in September?

Take your pick, but note the exceptional blues you might enjoy from SALA Samui Chaweng and surrounding resorts – I took the photo above in early September.

Where to find a good party in September?

As a quick starter-pack to find more humans:

Is September or October better on Koh Samui?

You'll likely have better (sunnier) weather in September than October – especially early September vs late October. However, if you don't like heat, you might prefer October's stronger breeze.

Koh Samui Airport in September

Is Koh Samui busy in September?

After August holidays, almost everyone else has returned to the real world with school and job commitments. You get the beaches to yourself.

Is Koh Samui or Phuket better in September?

Rainy season comes to Phuket in September and October. On Koh Samui it’s usually late October, November and part of December.

  • Temperature (avg): 28°C on Koh Samui vs 27°C in Phuket
  • Sunshine (hours): 6 on Koh Samui vs 7 in Phuket
  • Rainy days (avg): 11 days (130 mm) on Koh Samui vs 21 days (400 mm) in Phuket
  • Sea temperature: 28°C on Koh Samui vs 29°C in Phuket
Bophut Beach in September

What are hotel rates like for Koh Samui in September? How do they compare between September and October?



Between the four hotels, rates range from 90% to 132% between September and October. Not much of a surprise, there’s not a tremendous amount of difference in the experience until you reach the later half of October and it might get a bit stormy. Rates via Booking.com for a random night in September 2023.

When are sunrise and sunset on Koh Samui in September? What time does it get dark?

From September 1 to 30, sunrise shifts just a few minutes from 6:11am to 6:08am. If you're an early riser, you'll enjoy first light from about 5:20am. Prefer happy hour to anything athetic? Sunset is 6:29pm on September 1 and 6:11pm by the end of the month. Want to enjoy candelit dinners? Any reservations at 7:30pm onwards will be after dark.

Koh Samui in September

Time travel: Koh Samui in September 2006

The Koh Samui Guide: So how to plan your perfect trip? For beach-by-beach comparisons around Koh Samui, hotel ideas and tips for renting private villas, The Koh Samui Guide is invaluable in your trip-planning and your best friend when you get here.

“I bought your guide and it made my decision on which beach to choose much easier! I choose Chaweng and I had the most enjoyable vacation of my life.” – Shivan

Weather details via Weather Spark, which promises that “snow is exceptionally unlikely to fall at this location in September”.