Seoul is warmest in August, averaging 29° by day and 22° at night. The wettest month is July with 338 mm, and the year brings about 1494 mm in total.
Month by month
| Month | High | Low | Rain | Sea | Daylight | Good for |
|---|---|---|---|---|---|---|
| January | 2° | -7° | 31 mm | 4° | 9.7 h | Cool |
| February | 5° | -5° | 28 mm | 3° | 10.6 h | Cool |
| March | 11° | -1° | 50 mm | 6° | 11.7 h | Cool |
| April | 17° | 5° | 54 mm | 10° | 13.0 h | Sightseeing |
| May | 21° | 11° | 112 mm | 14° | 14.0 h | Mild |
| June | 26° | 17° | 198 mm | 19° | 14.6 h | Rainy season |
| July | 28° | 21° | 338 mm | 23° | 14.4 h | Rainy season |
| August | 29° | 22° | 329 mm | 26° | 13.5 h | Rainy season |
| September | 26° | 17° | 183 mm | 24° | 12.2 h | Rainy season |
| October | 19° | 10° | 71 mm | 20° | 11.0 h | Sightseeing |
| November | 12° | 3° | 72 mm | 14° | 9.9 h | Cool |
| December | 3° | -5° | 28 mm | 8° | 9.4 h | Cool |
High and low are average daily maximum and minimum, rain is typical monthly total, sea is the average surface temperature, daylight is the hours between sunrise and sunset mid-month. Climate normals from NASA POWER and NOAA MUR — averages, not promises.
When to go
Beach weather: No month in Seoul combines swimming warmth with dry skies.
Walking the city: April and October — highs of 17–19° and no more than 71 mm of rain a month.
Wet season: June, July, August and September — up to 338 mm in a single month.