Thailand Sun UV Index by Month
UV index, SPF recommendation, and sun-hour windows by city and activity.
What this solves
Thailand's UV index regularly hits 11+ (extreme) from March to September. Chiang Mai has a unique "burning season" (Mar–May) where haze from agricultural burning compounds UV exposure. Phuket is equatorial — UV stays high year-round. SPF and timing matter as much as sunscreen.
How to read results
UV index 1–2 is low (no protection needed). 3–5 is moderate. 6–7 is high. 8–10 is very high (cover up). 11+ is extreme (avoid midday sun). Thailand hits 11+ in March–May for most cities. SPF 50+ is recommended, reapply every 2 hours.
Limitations
- UV index varies with cloud cover and elevation. Chiang Mai is higher altitude — more UV.
- Burning-season haze (Chiang Mai) is a separate air-quality concern.
- Specific daily UV reports are available from the Thai Meteorological Department.
FAQ
When is Chiang Mai burning season?
February through April. Agricultural burning in northern Thailand and Myanmar produces haze that can push PM2.5 over 200 µg/m³. Combine with UV 10–12, this is a serious health risk for sensitive groups.
Which SPF should I use?
SPF 30 minimum. SPF 50+ for the beach, hiking, or any extended outdoor activity. Reapply every 2 hours, or every hour if swimming or sweating.
Is the sun stronger in Phuket than Bangkok?
Yes — Phuket is closer to the equator and at sea level. Bangkok has slightly less direct UV due to haze. Chiang Mai is highest altitude (UV increases ~10% per 1000m) so has strong UV despite cooler weather.
Sources
- Thai Meteorological Department — published UV index daily reports.
- WHO — UV index safety recommendations.
- Pollution Control Department — Chiang Mai PM2.5 monitoring.