Seoul in September
In September, Seoul averages 26°C (79°F) during the day and 17°C (63°F) at night, with around 9 days of rain (170 mm total).
High seasonConditions are warm and beach-friendly. Occasional showers are likely but won't dominate.
September is a great month to visit Seoul: pleasant temperatures and relatively few wet days.
How September compares to the rest of the year in Seoul
September is in the middle of the year for warmth in Seoul (4th of 12) and moderately rainy compared to the rest of the year (6th of 12). Daytime temperature runs 9°C above the annual average (17°C). September runs 4°C cooler than August (30°C) and cools 7°C in October (19°C).
September sunrise & sunset in Seoul
Times shown for Seoul local time (Asia/Seoul), calculated for the 15th of September. They shift by a few minutes day to day across the month.
Photography light in Seoul — September
Golden-hour and blue-hour windows for the 15th of September, in Seoul's local time. Use these for soft warm light (golden) or cool architectural twilight (blue).
📅 When to book — Seoul in September
Travel writers usually only tell you when to go. Here's when to book flights and lodging for the best mix of price and availability, based on September's tier (High season) and Seoul's popularity.
September in South Korea — events that affect travel
Known cultural, religious, or national events that surge prices, fill hotels, or close businesses during this month. Plan around them, or build your itinerary around the ones you'd like to see.
Korea's major harvest festival — most Koreans travel home; Seoul empties out somewhat but transit out of the city books solid.
Plan: Good time to enjoy a quieter Seoul; bad time to try to take a KTX train south on the holiday's eve.
Crowds & pricing — September in Seoul
This is a busy month in Seoul — not the absolute peak, but tourist numbers are clearly elevated. You'll feel it at headline attractions on weekends and in the historic centre, though side streets and lesser-known sights stay manageable. Prices are above off-season but not at their summit. A good week for first-time visitors who want everything open without the worst of the crush.
Why this tier: excellent tourism weather
Sun & mosquito risk — September in Seoul
UV is a clear-sky sea-level estimate — clouds, altitude, and reflective surfaces (snow, water) shift it ±30%. Mosquito risk is climate-derived only; for current disease advisories (dengue, malaria, zika) check the CDC or WHO travel pages before your trip.
Seoul in other months
| Month | Avg high | Avg low | Rainfall | Rain days | Snow days |
|---|---|---|---|---|---|
| January | 2°C / 36°F | -6°C / 21°F | 20 mm | 7 | 3 |
| February | 4°C / 39°F | -3°C / 27°F | 25 mm | 7 | 2 |
| March | 10°C / 50°F | 1°C / 34°F | 45 mm | 8 | — |
| April | 17°C / 63°F | 7°C / 45°F | 75 mm | 9 | — |
| May | 23°C / 73°F | 13°C / 55°F | 105 mm | 10 | — |
| June | 27°C / 81°F | 18°C / 64°F | 130 mm | 11 | — |
| July | 29°C / 84°F | 22°C / 72°F | 395 mm | 16 | — |
| August | 30°C / 86°F | 22°C / 72°F | 365 mm | 14 | — |
| September | 26°C / 79°F | 17°C / 63°F | 170 mm | 9 | — |
| October | 19°C / 66°F | 10°C / 50°F | 55 mm | 6 | — |
| November | 11°C / 52°F | 3°C / 37°F | 55 mm | 8 | 1 |
| December | 4°C / 39°F | -3°C / 27°F | 20 mm | 7 | 3 |
Other cities with similar September weather
🌍 See the full ranked list of climate twins for Seoul in September →
Frequently asked questions
How hot is Seoul in September?
In September, Seoul averages a high of 26°C (79°F) and a low of 17°C (63°F) — generally warm.
Does it rain a lot in Seoul in September?
September sees occasional rain in Seoul, with about 9 rainy days on average.
Is September a good time to visit Seoul?
September is warm. It suits travelers who are comfortable with warm weather; check the month-by-month ranking to compare it against the rest of the year.
What should I pack for Seoul in September?
Pack light layers for warm days and cooler evenings. See the full September packing list for Seoul for a complete, climate-based checklist.
Check the live 10-day forecast and sunrise/sunset.