Thailand UV Index by Month: At a Glance
Thailand straddles the tropics from 6° to 20° north, so UV stays elevated all year. The dry season (November–February) is the safest window in terms of comfort, while the pre-monsoon spike (March–May) produces the most dangerous burn conditions of the year.
This guide uses live and historical UV data from specialized UV monitoring services and public weather data sources, cross-referenced with WHO UV Index thresholds, to show you exactly when burn risk is highest and lowest in Thailand.
Monthly UV Averages for Thailand
The table below shows average peak UV index by month for Thailand, the WHO risk category, and the typical burn time for Fitzpatrick skin type II (fair skin, light hair) with no protection at solar noon.
| Month | Avg Peak UV | Risk Level | Burn Time (Skin Type II) |
|---|---|---|---|
| January | 10 | Very High | 7 min |
| February | 11 | Extreme | 6 min |
| March | 12 | Extreme | 6 min |
| April | 12 | Extreme | 6 min |
| May | 12 | Extreme | 6 min |
| June | 11 | Extreme | 6 min |
| July | 11 | Extreme | 6 min |
| August | 11 | Extreme | 6 min |
| September | 11 | Extreme | 6 min |
| October | 10 | Very High | 7 min |
| November | 9 | Very High | 7 min |
| December | 9 | Very High | 7 min |
Use these numbers as a planning baseline. For live, location-specific UV at any time of day, check the Thailand UV index page on Daily UV Tracker — it pulls real-time data and adjusts burn time for your skin type.
Best Months to Visit Thailand for Sun Safety
The best months to visit Thailand from a UV-safety standpoint are November to February. During this window, the cool, dry season pairs slightly lower UV with clearer skies, ideal for beach holidays in Phuket, Krabi and Koh Samui. UV bottoms out around 9 in November, which classifies as very high risk under WHO guidelines.
For most travellers — particularly those with Fitzpatrick I, II or III skin types — these months allow for longer outdoor windows with conventional SPF 30 protection, fewer mid-afternoon retreats indoors, and a far lower risk of trip-ending sunburn. They also tend to coincide with shoulder-season pricing in Thailand, making them a smart pick for budget-conscious travellers as well as sun-sensitive ones.
That said, even the "best" months in tropical destinations require constant SPF — UV rarely drops below 8. Use the burn time calculator to see what your skin can actually handle on any given day.
Worst Months to Visit Thailand for Sun Safety
The worst months to visit Thailand for UV safety are March to May. These are the months when pre-monsoon Thailand sees the year's highest UV combined with extreme heat — burn times can drop below 10 minutes for fair skin. UV peaks at 12 in March, which sits firmly in the extreme risk band on the WHO scale.
For Fitzpatrick I and II skin types, unprotected burn times in March can drop to 6 min or less at solar noon. For darker skin types (IV–VI), the visible burn risk is lower, but DNA-level UV damage and long-term skin cancer risk remain significant — UV 11+ is genuinely dangerous regardless of skin tone.
If you must travel to Thailand during these months, the safest pattern is to:
- Plan outdoor activities for the first three hours after sunrise, when UV is still climbing.
- Treat 10am to 4pm as a strict shade-or-indoors window unless wearing UPF clothing.
- Layer mineral SPF 30+ with a wide-brim hat and wraparound sunglasses.
- Reapply sunscreen every 90 minutes, not the standard two hours, in extreme UV environments.
- Check the live UV forecast every morning — afternoon clouds can hide UV 11 conditions.
See our full tropical sun safety guide for more on this pattern.
Month-by-Month Breakdown for Thailand
Below is a quick read of what to expect each month in Thailand, ordered by season:
Peak UV: March (UV 12)
This is the most dangerous month for unprotected sun exposure in Thailand. Treat every outdoor activity as a high-risk burn window and consider rescheduling beach days for early morning or late afternoon.
Lowest UV: November (UV 9)
This is the safest month to be outdoors in Thailand. UV is still high enough to require active sun protection, but the risk window is far narrower than in peak months.
Shoulder months
The transition months — typically the period either side of March — give you most of the climate benefits of peak season with substantially lower UV. Look closely at the table above to find the sweet spot for your trip.
How Thailand Compares to Other Destinations
Thailand sits in the Southeast Asia region with a tropical climate. Compared to other popular destinations:
- Phuket, Chiang Mai, Krabi — nearby cities with similar UV profiles to Thailand.
- Bali and the Maldives — equatorial benchmarks at UV 11–12 year-round.
- Sydney and Perth — Southern Hemisphere extremes with thinner ozone.
- All destinations — full directory of UV profiles.
For a structured month-by-month view across countries, see our destinations by month hub.
Frequently Asked Questions
What is the UV index in Thailand right now?
Live UV in Thailand changes hour by hour and varies by exact location. Check the Thailand live UV page for the current reading and a 16-day forecast.
When is Thailand safest for fair skin?
Thailand is safest for Fitzpatrick I–III skin types during November to February, when peak UV drops to 9–11. Even then, SPF 30, a hat and shade between 11am and 3pm are recommended.
What month has the highest UV index in Thailand?
March typically records the highest UV in Thailand, averaging UV 12 at solar noon. This corresponds to the WHO extreme risk category.
Is Thailand safe to visit during the worst UV months?
Yes — millions of people visit Thailand during March–May every year. The risk is manageable with disciplined sun protection: avoid midday sun, wear UPF clothing, and reapply SPF 30+ every 90 minutes.
How does Thailand's UV compare to home?
For most travellers from northern Europe, the UK or the northern US, Thailand's peak UV (12) is two to three times higher than what you experience at home in summer. Burn times can be a fraction of what you're used to.
Sources and Methodology
UV averages in this guide are derived from:
- Specialized UV monitoring services — global real-time UV index data, used for current and forecast UV on Daily UV Tracker.
- Public weather data sources — historical hourly UV and weather data spanning multiple years per location.
- WHO UV Index reference — risk categorisation thresholds.
- US EPA UV Index Scale — burn time guidance by skin type.
Burn times shown for skin type II use the standard 67 minutes ÷ UV formula and assume no sunscreen, no clothing and clear-sky conditions at solar noon. Real-world burn times vary substantially with altitude, water reflection, ozone and individual skin response — always cross-reference the live Thailand UV forecast and the burn time calculator before any extended outdoor activity.
Key Takeaways
- The best months to visit Thailand for UV safety are November to February, when UV averages 9–11.
- The worst months are March to May, when UV climbs to 12 in March.
- Northern Hemisphere summer (Jun–Aug) is the peak UV window.
- Always check the live Thailand UV index before planning outdoor activity, and adjust your protection accordingly.
- Combine the monthly averages above with the personalised burn time calculator for the most accurate planning.