Thailand (Koh Samui) · May
Low seasonThailand · Asia
Climate Overview
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Ø day, range from coolest to warmest dayØ dayrange | 31° (88°)27– (81–)32 (90) | 31° (88°)29– (84–)32 (90) | 32° (90°)29– (84–)34 (93) | 33° (91°)29– (84–)35 (95) | 34° (93°)31– (88–)35 (95) | 33° (91°)30– (86–)35 (95) | 33° (91°)30– (86–)34 (93) | 33° (91°)30– (86–)34 (93) | 33° (91°)29– (84–)34 (93) | 32° (90°)28– (82–)34 (93) | 31° (88°)27– (81–)33 (91) | 31° (88°)27– (81–)33 (91) |
Ø night, range from coldest to warmest nightØ nightrange | 26° (79°)22– (72–)27 (81) | 26° (79°)23– (73–)27 (81) | 27° (81°)24– (75–)28 (82) | 27° (81°)24– (75–)29 (84) | 27° (81°)24– (75–)28 (82) | 27° (81°)24– (75–)28 (82) | 27° (81°)24– (75–)28 (82) | 27° (81°)24– (75–)28 (82) | 27° (81°)24– (75–)27 (81) | 26° (79°)24– (75–)27 (81) | 26° (79°)24– (75–)27 (81) | 26° (79°)23– (73–)27 (81) |
☀️Sunshine | 8h UV 8 | 9h UV 9 | 10h UV 9 | 9h UV 9 | 8h UV 9 | 8h UV 8 | 7h UV 8 | 8h UV 8 | 6h UV 8 | 6h UV 7 | 6h UV 7 | 7h UV 7 |
🌊Water Temp | 28° (82°) | 29° (84°) | 30° (86°) | 31° (88°) | 31° (88°) | 30° (86°) | 30° (86°) | 30° (86°) | 30° (86°) | 30° (86°) | 29° (84°) | 28° (82°) |
🌧Rain Days | 8d154mm (6.1") | 4d66mm (2.6") | 4d112mm (4.4") | 6d101mm (4.0") | 11d152mm (6.0") | 10d120mm (4.7") | 11d142mm (5.6") | 8d95mm (3.8") | 11d122mm (4.8") | 15d239mm (9.4") | 16d474mm (18.7") | 11d310mm (12.2") |
Best travel time current monthØ = average · small figures = range: coolest–warmest day / coldest–warmest nightClimate data 2005–2025 · Source: ERA5 + station data
Post-season — prices falling after the travel period, beaches and attractions quieter.
May in Thailand (Koh Samui) is generally manageable, but with 11 rain days it's not a reliably sunny month. Better conditions can be found in February, March, April, and August.
Daytime highs reach 34°C (93°F) with a daily average of 30°C (86°F) — nights stay warm at 27°C (81°F). Peaks reach around 35°C (95°F), the coldest nights around 24°C (75°F). The sun shines an average of 8 hours per day; there are 11 rain days with 152 mm (6.0 in) total. The water is a warm 31°C (88°F) — perfect for snorkelling and swimming.
Sun protection, a hat, and plenty of water are essential at these temperatures. Plan activities for early morning or evening.
Events & Festivals
- Samui Regattavaries (late May, 8 days)
Asia's most prestigious sailing regatta off Chaweng Beach. Yachts from around the world compete over several race days, with sundowner parties on the beaches in the evenings. The event is part of the international sailing calendar.
Packing list for Thailand (Koh Samui) in May
- Airy linen or cotton clothing
- Light evening wear
- Swimwear and beach towel
- SPF 50 sunscreen
- Sunglasses
- Sun hat
- Light umbrella or rain poncho
- Insect repellent
- Travel first-aid kit
Frequently Asked Questions
- Is May a good time to visit Thailand (Koh Samui)?
- May is not an optimal month for Thailand (Koh Samui) (Score: 67/100), but it is manageable. For better conditions, consider February, March, April, and August.
- How warm is it in Thailand (Koh Samui) in May?
- In May, Thailand (Koh Samui) sees daily highs of 34°C (93°F). Nights cool to 27°C (81°F), with a daily average of 30°C (86°F). Peaks reach around 35°C (95°F), the coldest nights around 24°C (75°F).
- How much rain falls in Thailand (Koh Samui) in May?
- In May, Thailand (Koh Samui) receives an average of 152 mm (6.0 in) of rain over 11 rain days. An umbrella may occasionally be needed.
- How many sunshine hours does Thailand (Koh Samui) get in May?
- Thailand (Koh Samui) averages 8 sunshine hours per day in May — above the annual average.
- How warm is the water in Thailand (Koh Samui) in May?
- Water temperature in Thailand (Koh Samui) in May averages 31°C (88°F) — ideal for swimming and snorkelling.
