UV index in Seoul in September
In September, the UV index in Seoul typically peaks around 5.2 at midday — moderate on the WHO scale — with individual days reaching 7 in recent years. Sun protection is needed around the middle of the day.
How fast would you burn?
Estimated time to sunburn in unprotected midday sun at UV 5.2:
| Skin type | Time to burn |
|---|---|
| I — Very fair | ~26 min |
| II — Fair | ~32 min |
| III — Medium | ~45 min |
| IV — Olive | ~58 min |
Estimates from typical minimal erythemal doses — see methodology. Darker types (V–VI) burn slower still. Reflection off water or sand shortens all of these.
What to do about it
- Pack SPF 30+ and use it for extended midday time outside — fair skin can burn in under an hour at these levels.
- Mornings and late afternoons are generally low-risk without protection.
- Sunglasses are worth it: cumulative UV drives cataracts even at moderate levels.
Planning a trip? Check the live UV index in Seoul closer to your dates — day-to-day cloud cover moves the real number around this average.
Seoul's UV year at a glance
| Month | Typical midday peak | Level |
|---|---|---|
| January | 2.8 | Low |
| February | 3.7 | Moderate |
| March | 5 | Moderate |
| April | 5.9 | Moderate |
| May | 6.4 | High |
| June | 6.9 | High |
| July | 6.6 | High |
| August | 6.7 | High |
| September | 5.2 | Moderate |
| October | 3.8 | Moderate |
| November | 3.2 | Moderate |
| December | 2.6 | Low |
The strongest month is June (typical peak 6.9); the gentlest is December (typical peak 2.6).
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