Vitamin D in Thailand in May: sun, UV and what to expect
Too hot Too hot here in May: afternoon highs average 34°C (feels like 41°C). Heat stress is a real risk, so a beach stay is not recommended. Try another month or destination.
7.7 hsun window (UV 2.5+)
8.1peak UV Index
7 minto a full dose
34°Cafternoon high
20/30rainy days
25/30sunny days
The country rating is for a typical beach, but some places in Thailand still work in May: Ko Tao (excellent).
How long in the sun in May?
- If you travel anyway, plan your sun session around midday (roughly 11:00 to 15:00), when the UV Index peaks at about 8.1. With about a quarter of your skin bare, a full dose takes around 7 minutes for skin type III at age 30, and about 12 minutes at age 65.
- Stop well before your skin turns pink. At this UV level skin type III can start to burn after about 25 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 9.1, 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 | 4 min | 8 min | 16 min |
| Type II | 5 min | 10 min | 21 min |
| Type III | 7 min | 12 min | 25 min |
| Type IV | 10 min | 19 min | 37 min |
| Type V | 13 min | 25 min | 49 min |
| Type VI | 22 min | 41 min | 82 min |
Minutes at midday for about 1,000 IU of vitamin D with a quarter of the body bare, at Bangkok, 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 May
| Place | Rating | Sun window | Full dose | Afternoon high | Rainy days |
|---|---|---|---|---|---|
| Ko Tao | Excellent | 7.9 h | 7 min | 31°C | 16/30 |
| Pattaya | Too hot | 8.0 h | 7 min | 33°C | 17/30 |
| Ko Samet | Bad weather | 7.8 h | 7 min | 32°C | 20/30 |
| Ko Samui | Too hot | 7.8 h | 7 min | 32°C | 19/30 |
| Ao Nang | Bad weather | 7.3 h | 7 min | 31°C | 23/30 |
| Ko Lipe | Bad weather | 7.6 h | 7 min | 31°C | 25/30 |
| Chiang Mai | Too hot | 7.7 h | 6 min | 34°C | 23/30 |
| Ko Pha Ngan | Too hot | 7.8 h | 7 min | 32°C | 19/30 |
| Ko Phi Phi | Bad weather | 7.4 h | 7 min | 31°C | 24/30 |
| Bangkok | Too hot | 7.7 h | 7 min | 34°C | 20/30 |
| Ko Chang | Too hot | 7.6 h | 7 min | 32°C | 21/30 |
| Khao Lak | Too hot | 7.5 h | 7 min | 33°C | 22/30 |
| Ko Lanta | Bad weather | 7.5 h | 7 min | 31°C | 24/30 |
| Hua Hin | Too hot | 7.5 h | 7 min | 34°C | 19/30 |
| Krabi | Too hot | 7.5 h | 7 min | 32°C | 25/30 |
| Railay Beach | Too hot | 7.3 h | 7 min | 33°C | 23/30 |
| Phuket | Too hot | 7.7 h | 7 min | 32°C | 24/30 |
| Ayutthaya | Too hot | 7.7 h | 7 min | 36°C | 21/30 |
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