Phuket or Koh Samui in July?
On climate data, Phuket comes out ahead overall in July. See the per-criterion details below.
PhuketPhoto: PavF · CC BY-SA 3.0
Koh SamuiPhoto: Sonia Selivonchik · CC BY-SA 4.0Key figures in July
| Criterion | Phuket | Koh Samui |
|---|---|---|
| Average daily high | 28 °C | 29 °C |
| Average daily low | 27 °C | 28 °C |
| Sea | 29 °C | 30 °C ★ |
| Rainy days | 27 rainy days (est.) | 27 rainy days (est.) |
| Sun | 6 h/day | 6 h/day |
| Humidity | 83 % | 80 % |
Winner by travel type
Phuket or Koh Samui in July: the short answer
In July, Phuket comes out ahead on the overall climate score (Phuket 55/100 vs Koh Samui 54/100). That is a snapshot of one month, though — which one truly fits depends on what you want from the trip, so the breakdown below goes criterion by criterion.
This comparison focuses on July as a representative month for the pair; for any other month, use each destination's month-by-month pages. Across the whole year Phuket averages a climate score of 60/100, Koh Samui 61/100. Both profiles below are historical monthly averages, not a forecast.
Weather in July, side by side
The average daily high is about 28 °C in Phuket and 29 °C in Koh Samui — warmer in Koh Samui. Average daily lows are around 27 °C versus 28 °C.
On rain, Phuket sees about 27 rainy days in July and Koh Samui about 27. Sunshine is comparable (6 vs 6 hours a day).
Sea temperature and swimming
In July the water is about 29 °C at Phuket and 30 °C at Koh Samui — warmer for swimming at Koh Samui. Over the year, Phuket is comfortable for swimming (from ~21 °C) in January, February, March, April, May, June, July, August, September, October, November and December, Koh Samui in January, February, March, April, May, June, July, August, September, October, November and December. Peak sea warmth is May for Phuket and May for Koh Samui.
Rain and sun across the year
Over a full year Phuket records roughly 261 rainy days and Koh Samui about 246 — the drier of the two overall is Koh Samui. At their sunniest, Phuket reaches about 8 hours of sun a day (March) and Koh Samui about 8 (March). If dependable dry, sunny weather is your top priority, weigh these annual totals alongside the single month above.
Best time to visit each
Climatically, Phuket is at its best in January, February, March and December, while Koh Samui peaks in January, February, March and December. If your dates are fixed, pick the destination whose strong season overlaps them; if you are flexible, plan around these windows.
Which suits which kind of trip
Based on the July scores for each travel style:
Beach & swimming: Phuket scores higher in July (Phuket 67 vs Koh Samui 65).
City breaks: Phuket scores higher in July (Phuket 50 vs Koh Samui 48).
Active & hiking: Phuket scores higher in July (Phuket 37 vs Koh Samui 36).
Family: Phuket scores higher in July (Phuket 58 vs Koh Samui 56).
Verdict: which should you pick?
In July, Phuket leads across every scored category here — the overall score and each travel type — so on the climate data it is the clearer pick this month. Over the year, Koh Samui carries the higher overall climate score. Your own priority (sun, sea, low rain or sightseeing comfort) still matters, and the month-by-month pages for each destination give you the full picture before you book.