Ulsan is warmest in August, averaging 29° by day and 24° at night. The wettest month is July with 267 mm, and the year brings about 1322 mm in total.
Month by month
| Month | High | Low | Rain | Sea | Daylight | Good for |
|---|---|---|---|---|---|---|
| January | 7° | -0° | 53 mm | 14° | 9.8 h | Cool |
| February | 9° | 2° | 50 mm | 13° | 10.7 h | Cool |
| March | 13° | 5° | 78 mm | 13° | 11.7 h | Mild |
| April | 17° | 9° | 87 mm | 15° | 12.9 h | Sightseeing |
| May | 21° | 14° | 84 mm | 17° | 13.9 h | Sightseeing |
| June | 24° | 18° | 177 mm | 20° | 14.4 h | Mild |
| July | 27° | 22° | 267 mm | 23° | 14.2 h | Rainy season |
| August | 29° | 24° | 202 mm | 27° | 13.3 h | Rainy season |
| September | 26° | 20° | 180 mm | 25° | 12.2 h | Rainy season |
| October | 21° | 15° | 65 mm | 22° | 11.1 h | Sightseeing |
| November | 16° | 9° | 51 mm | 19° | 10.1 h | Mild |
| December | 8° | 2° | 28 mm | 16° | 9.6 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 Ulsan combines swimming warmth with dry skies.
Walking the city: April, May and October — highs of 17–21° and no more than 87 mm of rain a month.
Wet season: July, August and September — up to 267 mm in a single month.