Ulsan, South Korea experiences average highs of 18°C (64°F) and lows of 12°C (54°F) throughout the year. Rainfall is moderate, averaging about 8 rainy days per month. Sunshine is abundant, averaging about 9 hours per day. Average highs have warmed by 0.8°C (1.4°F) across the available records.
Ulsan, South Korea Weather & Climate 2026
Monthly climate averages for Ulsan, South Korea. Based on 10-year ERA5 reanalysis data.
Climate Overview
Drier season: Jan–Dec 
Wetter season: Jun–Sep At-a-Glance Climate Summary
Live Weather & Air Quality
Key figures
Climate Score
5.9/10
Best: April, May, June, September, October
UV Index
5
Low
Temperature 18°C / 12°C
Feels Like 18°C / 10°C
Rainy Days 8
Rainfall 109 mm
Sunshine 9 h
Humidity 71%
Wind Speed 18 km/h
Dew Point 10°C
Snow Days 1 days
Frost Days 9 days
Hottest Month
30°C
August
Avg Low25°C
Rain15days
Coldest Month
-1°C
January
Avg High6°C
Rain4days
Driest Month
3days
November
Avg High15°C
Avg Low7°C
Windiest Month
19 km/h
April (Gusts 44)
Sea Temperature
12°C – 27°C
Warmest water: August (
26.5°C
)
Worst Time to Visit
Consider avoiding January, February, August, December due to less favorable weather conditions.
Sun Position
Sunrise 05:08
Daylight 14.5h
Sunset 19:41
Live conditions—
Ulsan on the map · live conditions
Ulsan, South Korea
- Continent
- Asia
- Country
- South Korea
- City
- Ulsan
- Population
- 1.1M
- Coordinates
- 35.54°, 129.32°
Seasonal Breakdown
Spring
Mar–May
Avg High 18°C
Avg Low 9°C
Rain 8 days/mo
2/3 best months
Summer
Jun–Aug
Avg High 28°C
Avg Low 22°C
Rain 13 days/mo
1/3 best months
Autumn
Sep–Nov
Avg High 20°C
Avg Low 14°C
Rain 8 days/mo
2/3 best months
Winter
Dec–Feb
Avg High 8°C
Avg Low 0°C
Rain 4 days/mo
Climate Charts
Based on historical averages (2016–2025)
Monthly Temperatures
HighLowShaded bands show the typical range across the available yearly records.
Line chart showing monthly temperatures. Jan: 6°C / -1°C . Feb: 9°C / 1°C . Mar: 13°C / 5°C . Apr: 18°C / 9°C . May: 22°C / 14°C . Jun: 25°C / 19°C . Jul: 28°C / 23°C . Aug: 30°C / 25°C . Sep: 25°C / 21°C . Oct: 20°C / 15°C . Nov: 15°C / 7°C . Dec: 8°C / 1°C .
Monthly Rainfall
Rainfall
Bar chart showing monthly rainfall. Jan: 35 mm. Feb: 44 mm. Mar: 77 mm. Apr: 93 mm. May: 92 mm. Jun: 149 mm. Jul: 203 mm. Aug: 202 mm. Sep: 233 mm. Oct: 108 mm. Nov: 40 mm. Dec: 28 mm.
Monthly Humidity
Humidity
Line chart showing monthly humidity. Jan: 57%. Feb: 58%. Mar: 66%. Apr: 69%. May: 73%. Jun: 81%. Jul: 87%. Aug: 84%. Sep: 82%. Oct: 74%. Nov: 67%. Dec: 59%.
Monthly Wind Speed
Wind SpeedGusts
Bar chart showing monthly wind speed. Jan: 19 km/h . Feb: 19 km/h . Mar: 18 km/h . Apr: 19 km/h . May: 18 km/h . Jun: 16 km/h . Jul: 16 km/h . Aug: 17 km/h . Sep: 18 km/h . Oct: 17 km/h . Nov: 17 km/h . Dec: 19 km/h .
Sunshine
Sunshine
Sunshine: Jan: 8h. Feb: 8h. Mar: 9h. Apr: 9h. May: 10h. Jun: 9h. Jul: 9h. Aug: 10h. Sep: 8h. Oct: 8h. Nov: 8h. Dec: 8h.
Sea Temperature
Sea Temperatureswim
Line chart showing monthly sea temperature. Jan: 12°C . Feb: 12°C . Mar: 13°C . Apr: 14°C . May: 16°C . Jun: 18°C . Jul: 20°C . Aug: 27°C . Sep: 26°C . Oct: 22°C . Nov: 18°C . Dec: 14°C .
UV Index
UV Index
Bar chart showing monthly UV index. Jan: UV 3. Feb: UV 4. Mar: UV 5. Apr: UV 6. May: UV 6. Jun: UV 7. Jul: UV 7. Aug: UV 7. Sep: UV 5. Oct: UV 4. Nov: UV 3. Dec: UV 3.
Monthly Daylight Hours
Daylight12h reference
Monthly Dew Point & Comfort
Dew Point Dry Comfortable Humid Muggy
Snow Days
Snow DaysSnowfall
Snow Days: Jan: 1 days. Feb: 1 days. Mar: 1 days. Apr: 0 days. May: 0 days. Jun: 0 days. Jul: 0 days. Aug: 0 days. Sep: 0 days. Oct: 0 days. Nov: 0 days. Dec: 0 days.
Climate Trends
Average highs have warmed by 0.8°C (1.4°F) across the available records. Average rainfall is trending drier by about 46 mm.
2016 to 2025
Avg high Avg rainfall
Climate summary
| Last 12 months | All years | |
|---|---|---|
| Hottest month | Aug 2025 · 31°C | Aug · 30°C |
| Coldest month | Feb 2025 · -2°C | Jan · -1°C |
| Wettest month | Aug 2025 · 191 mm | Sep · 233 mm |
| Windiest month | Apr 2025 · 20 km/h | Apr · 19 km/h |
Month-by-Month Weather Table
January
Poor 
February
Poor March
Fair April best
Good May best
Excellent June best
Excellent July
Wet August
Wet September best
Excellent October best
Excellent November
Good December
Poor | Month | Temp | Feels Like | Rain | Sun | Humidity | UV | Status | Details |
|---|---|---|---|---|---|---|---|---|
| January | 6°C / -1°C | 2°C / -6°C | 4days (35 mm) Good | 7.8h Good | 57% Moderate | 3 Moderate | Poor | View Details |
| February | 9°C / 1°C | 4°C / -4°C | 5days (44 mm) Good | 8.4h Good | 58% Moderate | 3.6 Moderate | Poor | View Details |
| March | 13°C / 5°C | 11°C / 2°C | 8days (77 mm) Wet | 8.9h Good | 66% Muggy | 4.8 Moderate | Fair | View Details |
| April best | 18°C / 9°C | 16°C / 7°C | 8days (93 mm) Wet | 9.4h Good | 69% Muggy | 5.7 High | Good | View Details |
| May best | 22°C / 14°C | 22°C / 13°C | 8days (92 mm) Wet | 10h Excellent | 73% Muggy | 6.4 High | Excellent | View Details |
| June best | 25°C / 19°C | 28°C / 20°C | 9days (149 mm) Wet | 9.4h Good | 81% Humid | 6.6 High | Excellent | View Details |
| July | 28°C / 23°C | 33°C / 27°C | 14days (203 mm) Wet | 9h Good | 87% Very Muggy | 6.8 High | Wet | View Details |
| August | 30°C / 25°C | 35°C / 29°C | 15days (202 mm) Wet | 9.7h Good | 84% Humid | 6.8 High | Wet | View Details |
| September best | 25°C / 21°C | 28°C / 23°C | 14days (233 mm) Wet | 7.6h Good | 82% Humid | 5.3 High | Excellent | View Details |
| October best | 20°C / 15°C | 20°C / 13°C | 7days (108 mm) Good | 7.8h Good | 74% Muggy | 3.9 Moderate | Excellent | View Details |
| November | 15°C / 7°C | 12°C / 4°C | 3days (40 mm) Excellent | 8.1h Good | 67% Muggy | 3.4 Moderate | Good | View Details |
| December | 8°C / 1°C | 4°C / -4°C | 4days (28 mm) Good | 7.9h Good | 59% Moderate | 2.7 Moderate | Poor | View Details |
Compare Nearby City Climates
Frequently Asked Questions
The best months to visit Ulsan are April, May, June, September, October, when temperatures are comfortable and rainfall is at its lowest. This is based on 10-year climate averages for Ulsan, scoring temperature, rainfall, humidity, and sunshine hours.
The hottest month in Ulsan is August, with average daytime highs of 30°C (85°F). Plan outdoor activities for early morning or late afternoon if visiting during this period.
The coldest month in Ulsan is January, with average overnight lows of -1°C (31°F). Pack warm layers and expect shorter daylight hours during this period.
The wettest month in Ulsan is September, averaging 233mm of precipitation across 14 rainy days. An umbrella or waterproof jacket is essential.
The rainy season in Ulsan runs through August, July, September, with the heaviest rainfall in August. Based on 10-year averages for Ulsan.
Ulsan receives approximately 104 sunshine hours per year. The sunniest month is May with around 10 hours. Based on climate data for Ulsan.
The least favorable months to visit Ulsan are January, February, August, December, primarily due to less favorable weather conditions. For the best conditions, consider April, May, June, September, October instead.
The annual average UV index in Ulsan is 5, classified as moderate. Standard sun protection (sunscreen, hat) is recommended during prolonged outdoor exposure.
Average humidity in Ulsan is 71%, classified as moderate. Humidity levels are generally comfortable and should not affect outdoor activities for most people.
Yes — sea temperatures in August, September, October average 25°C (77°F), which is warm and comfortable for swimming and water activities.
Yes, Ulsan receives snow. Months with snowfall average 1 snow days and 1 cm (0 in) of accumulation, with about 9 frost days during winter.
Average wind speeds in Ulsan are 18 km/h (11 mph). The windiest month is April with peak winds reaching 19 km/h (12 mph) (gusts up to 44 km/h / 28 mph).
Ulsan averages 6 clear-sky days per month with overall cloud cover around 55%. The clearest skies occur in December.
The annual average dew point in Ulsan is 10°C (50°F), which feels pleasant with low humidity. Outdoor activities are comfortable year-round from a humidity standpoint.
Ulsan has a Humid Subtropical climate, classified as Cfa under the Köppen system. Temperate climates have mild winters and warm summers, with rainfall spread across the year and four distinct seasons.
The 'feels like' temperature in Ulsan ranges from 10°C (50°F) to 18°C (64°F) on average. The 'feels like' temperature closely matches the actual temperature throughout most of the year.
Yes, June is a great time to visit Ulsan. It earns a climate score of 8.4/10 with Excellent.
For June in Ulsan, pack Umbrella, Breathable clothing, Sunscreen (SPF 30+), Sun hat, Sunglasses. With average highs of 25°C (77°F) and 9 rainy days, these essentials will keep you comfortable.
Data Source
Climate data derived from ERA5 reanalysis (ECMWF), averaged over 2016–2025. Sea surface temperature from marine reanalysis data. Climate scores and seasonal estimates are computed by WorldStats.
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