Koh Samui vs Penang

Based on sunshine hours, rain days, comfortable temperatures, and humidity levels, Koh Samui edges ahead as the better destination in September. Koh Samui offers 9 hours of daily sunshine with only 22 rain days, while Penang sees 9 sunshine hours and 26 rain days.

Koh Samui sits in the comfortable travel range at 26°C. Penang runs hot at 29°C.

For travelers who prioritize dry weather, Koh Samui is the stronger choice in September.

Koh Samui reaches an average high of 26°C (79°F) and drops to 23°C (73°F) at night during September. The daily temperature range is 3°C, meaning relatively stable temperatures from day to night.

Penang averages 29°C (84°F) for the high and 25°C (77°F) for the low, with a daily range of 4°C. The 3°C difference is noticeable but not dramatic.

Both cities are in the Northern Hemisphere, so they share the same seasonal pattern in September.

Koh Samui receives approximately 140 mm of rainfall across 22 rain days during September. Rain is frequent, so waterproof gear is essential.

Penang sees 250 mm over 26 rain days. That makes Koh Samui the drier option by 4 rain days and 110 mm of total precipitation.

Both cities share similar humidity levels at 82%.