Vitamin D in Thailand in September: sun, UV and what to expect
Bad weather Bad weather: it rains on about 27 days in September (rainy or monsoon season), so sun is hard to count on and a beach stay is not recommended.
6.5 hsun window (UV 2.5+)
7.5peak UV Index
7 minto a full dose
30°Cafternoon high
27/30rainy days
24/30sunny days
Open Thailand for September on the map Find stays in Thailand
How long in the sun in September?
- If you travel anyway, plan your sun session around midday (roughly 11:00 to 15:00), when the UV Index peaks at about 7.5. With about a quarter of your skin bare, a full dose takes around 7 minutes for skin type III at age 30, and about 13 minutes at age 65.
- Stop well before your skin turns pink. At this UV level skin type III can start to burn after about 27 minutes of midday sun, so cover up, find shade and use SPF 30+ on skin that stays out.
- On clear days the UV Index reaches about 9.2, which is very strong. Keep sessions short and protect the rest of the day.
- Water, sand and light surfaces reflect UV, so at the beach you get a little more sun than the number suggests, for the good and the bad.
| Skin type | Full dose, age 30 | Full dose, age 65 | Time to burn |
|---|---|---|---|
| Type I | 5 min | 9 min | 18 min |
| Type II | 6 min | 11 min | 22 min |
| Type III | 7 min | 13 min | 27 min |
| Type IV | 11 min | 20 min | 40 min |
| Type V | 14 min | 27 min | 53 min |
| Type VI | 24 min | 44 min | 89 min |
Minutes at midday for about 1,000 IU of vitamin D with a quarter of the body bare, at Phuket, the median coastal place. Time to burn is the time to reach one minimal erythemal dose and does not depend on age. A rough planning guide, not medical advice.
Places in Thailand in September
| Place | Rating | Sun window | Full dose | Afternoon high | Rainy days |
|---|---|---|---|---|---|
| Ko Samui | Bad weather | 7.1 h | 7 min | 30°C | 21/30 |
| Ko Tao | Bad weather | 7.0 h | 7 min | 29°C | 21/30 |
| Ko Pha Ngan | Bad weather | 7.1 h | 7 min | 30°C | 21/30 |
| Ko Phi Phi | Bad weather | 6.7 h | 7 min | 29°C | 25/30 |
| Ao Nang | Bad weather | 6.7 h | 7 min | 29°C | 26/30 |
| Krabi | Bad weather | 6.7 h | 7 min | 29°C | 26/30 |
| Hua Hin | Bad weather | 6.1 h | 7 min | 33°C | 20/30 |
| Ko Lipe | Bad weather | 6.5 h | 8 min | 29°C | 23/30 |
| Phuket | Bad weather | 6.5 h | 7 min | 30°C | 27/30 |
| Pattaya | Bad weather | 6.2 h | 7 min | 30°C | 26/30 |
| Chiang Mai | Bad weather | 6.3 h | 7 min | 30°C | 27/30 |
| Railay Beach | Bad weather | 6.6 h | 7 min | 29°C | 27/30 |
| Ko Chang | Bad weather | 6.7 h | 7 min | 29°C | 29/30 |
| Ko Lanta | Bad weather | 6.4 h | 8 min | 28°C | 27/30 |
| Ko Samet | Bad weather | 6.3 h | 8 min | 29°C | 25/30 |
| Bangkok | Bad weather | 6.4 h | 7 min | 32°C | 29/30 |
| Ayutthaya | Bad weather | 6.7 h | 7 min | 32°C | 29/30 |
| Khao Lak | Bad weather | 5.9 h | 8 min | 29°C | 28/30 |
Other months in Thailand
- Jan Excellent
- Feb Excellent
- Mar Excellent
- Apr Too hot
- May Too hot
- Jun Bad weather
- Jul Bad weather
- Aug Bad weather
- Sep Bad weather
- Oct Bad weather
- Nov Bad weather
- Dec Good
Best months: December to March. Full Thailand guide