WeatherJourney.com

Ulsan weather by month: averages, rainfall & climate trends

Seasons run to extremes in Ulsan: monthly means span 24.6°C between the coldest month and the warmest. The heavier rain months run from May to September. Ulsan weather by month: average temperatures, rainfall, extremes and how the climate has changed since 1940.

Today vs average

−1.9°Chigh below average

19° / 15°Today
21° / 13°Average
see today in detail →

How it's changed

+2.7°Caverage temperature, 2016–2025 vs 1940–1949average temperature vs 1940–4945frost days a year now (2016–2025) · 73 in the 1940sfrost days a year · 73 in the 1940s46days above 30°C a year now (2016–2025) · 16 in the 1940sdays above 30°C · 16 in the 1940s+2.7°C vs the 1940s · see how it's changed →
Weather by montha typical year, averaged over the full recordJanuary, rain 32 mmhigh 6°low −2°February, rain 43 mmhigh 8°low 0°March, rain 69 mmhigh 13°low 4°April, rain 98 mmhigh 18°low 9°May, rain 103 mmhigh 23°low 14°June, rain 161 mmhigh 25°low 19°July, rain 210 mmhigh 29°low 23°August, rain 183 mmhigh 30°low 24°September, rain 174 mmhigh 26°low 20°October, rain 69 mmhigh 21°low 13°November, rain 50 mmhigh 15°low 7°December, rain 27 mmhigh 9°low 1°wettest month July, 210 mm · 1,219 mm a yearsee month by month →

Right now

What it's doing today vs the historical average for this date.
Rain

Right now

18.5°

20°feels like
90%humidity
17°dew point
6 km/hfrom N
UV index0.0
sunrise06:33sunset17:41day length11h 09m
TueLight rain19°15°
WedPartly cloudy20°11°
ThuClear17°7°
FriOvercast20°12°
SatLight rain19°17°
SunLight rain20°18°
MonRain20°18°

On this date: October 19

Today (forecast)
19° / 15°
Average for October 19
21° / 13°

High below average · −1.9°C

  • Highest since 1940: 26.4° · 1997
  • Lowest since 1940: 6.7° · 2022
  • One year ago: 20° / 15°

Every October 19 in history, coldest to hottest

▲ Daily highs▼ Daily lows

Dots show daily highs (top) and lows (bottom) for each October 19 on record (n = 87). Outlined dots are today's forecast.

Area we sample

Each city's history comes from one ERA5 grid cell, about 28 km across, shown by the dashed box. Near mountains or coasts, conditions can vary across the cell.

Location & data

Historical weather for Ulsan is sampled from the ECMWF ERA5 reanalysis at 35.54°N, 129.32°E, with daily records since 1940.

Coordinates
35.54°N, 129.32°E
Time zone
Asia/Seoul
Period
1940–2026
Data source
ERA5 (ECMWF)

Last 30 days

23 of the last 31 days were warmer than the historical average for that date. Average difference: +1.6°C.

Each bar is one day, from morning low to afternoon high. Warm-colored bars are days whose mean ran above average; cool bars ran below. The dot inside the bar is the daily mean. The shaded band is the typical 10–90% range expected for that date. Average = the day's mean temperature averaged across every year of record (1940–2026) for that calendar date.

This date over the years

One dot per year, showing the mean temperature on this calendar date. Dots are warmer or cooler than the long-term average (dashed line); the shaded band is the typical 10–90% range, and the highlighted dot is today's forecast. Based on ERA5 reanalysis: modelled estimates, not station readings.

Weather by month

Average temperatures and rainfall for each month: a typical year, from the full record.

Climate overview

The year peaks in August, at around 29.8°C by mid-afternoon, with nights around 24.3°C. Around 105 nights a year stay above 20°C. The coolest month is January, when afternoons reach about 6.4°C and overnight lows sit around −1.6°C. Around 45 days a year dip below freezing.

The yearly total for Ulsan comes to about 1,219 mm; monthly amounts range from 27 mm in December up to 210 mm in July.

The record here starts in 1940, and since then the annual mean in Ulsan has climbed 2.7°C from the first ten years to the last ten. Days above 30°C have grown noticeably more frequent, from around 15 a year in the first decade to about 45 in the last.

Climate graph (climograph)

August is the warmest month, January the coolest: a yearly swing of 25°C. Wettest month: July (~210 mm). Whole year averages ~1,219 mm of rain.

Bars = average monthly rainfall (right axis). Lines = average daily high and low (left axis). Average = each month's value averaged across every year of record (1940–2026).

Rainy days by month

About 80 rainy days a year: most in July (~12), fewest in December (~3).

Bars = average number of days with ≥ 2 mm per month. Hover for the monthly rainfall total.

Monthly wind

Average daily peak wind at 10 m, by month.

Monthly solar energy

Average daily incoming solar energy in megajoules per square metre: the record's own proxy for how sunny the month is.

Ulsan month by month: what to expect

Typical conditions for each month, averaged across the full record (since 1940). Daylight is the time from sunrise to sunset. Highest and Lowest are the most extreme values in the ERA5 dataset (modelled since 1940), so they can differ from official weather-station readings.

MonthAvg highAvg lowRainRainy daysDaylightHighestLowest
January6.4°−1.6°32 mm39.8 h18.0° (2002)−14.2° (1967)
February8.4°0.1°43 mm410.7 h23.6° (2021)−12.5° (1957)
March12.9°4.0°69 mm611.7 h26.1° (2001)−7.9° (1977)
April18.3°9.0°98 mm712.9 h30.1° (1996)−1.8° (1972)
May22.8°13.8°103 mm713.9 h34.2° (2000)5.0° (1953)
June25.4°18.6°161 mm914.4 h33.5° (2005)9.2° (1981)
July28.7°23.4°210 mm1214.2 h37.2° (2013)15.7° (1966)
August29.8°24.3°183 mm1113.3 h38.6° (2013)14.8° (1972)
September25.9°19.7°174 mm1012.2 h35.4° (1994)9.9° (1957)
October21.2°13.2°69 mm411.1 h30.4° (2021)0.6° (1986)
November15.2°6.7°50 mm410.1 h27.2° (1979)−5.2° (1966)
December8.8°0.6°27 mm39.6 h20.9° (2023)−11.0° (1973)

How it's changed

Year-by-year signals from 1940 to today.

Climate stripes

Annual mean shifted from 1940–1949 to 2016–2025 by +2.7°C.

Each vertical stripe is one year. Color encodes how much that year's annual mean differed from the long-term average. Average = each year's annual mean compared to the average of all years (1940–2026). cooler ← → warmer

Annual mean temperature

Long-term trend: +0.31°C per decade.

One point per year, showing the temperature averaged across the whole year. The dashed line is the least-squares long-term trend. Based on ERA5 reanalysis: modelled estimates, not station readings.

Seasonal warming

Mar–May is warming fastest: +0.38°C per decade.

Each faint line is one three-month period's average per year; the bold dashed line is its long-term trend. Different parts of the year often warm at different rates. Based on ERA5 reanalysis: modelled estimates, not station readings.

Hot days vs frost days

Days ≥ 30°C per year: 16.0 early in the record → 45.9 recently. Frost days: 73 → 45.

Thin lines are raw yearly counts; thick lines are the smoothed trend that removes year-to-year noise. The hot-day threshold is auto-picked per city so the line actually moves. Average = a centered 5-year rolling average to smooth weather noise.

Yearly hot & cold extremes

Hottest day since 1940 in 2013, coldest in 1967: 38.6°C / −14.2°C.

One point per year: the single hottest and coldest day recorded that year.

Annual rainfall

~1,219 mm/year on average. Last decade: +9% vs that average. Long-term trend: +31 mm per decade.

One bar per year of total rainfall. Dashed line is the long-term average. Average = the average annual rainfall across every year of record (1940–2026).

Day-by-day grid

Each tiny square is one calendar day across the full record, about 30,000 days per city. Use the mode switch above the chart: Anomaly colors each day by how far it ran from the historical average for that date (red = warmer, blue = cooler), Daily mean temp shows the absolute mean temperature for the day (useful to see seasons and heatwaves), and Precipitation shows daily rainfall (useful to spot wet/dry seasons and droughts). Average = the long-term average for that calendar date (1940–2026).

Frequently asked questions about Ulsan

Which is the warmest month in Ulsan?
On long-term average, the warmest month in Ulsan is August (mean daily temperature of about 26.8°C) and the coolest is January (about 2.2°C).
How does today's temperature in Ulsan compare to the historical average?
On October 19, 2026, Ulsan is forecast to reach a high of 18.8°C and a low of 15.1°C. The long-term average for this date (the full record since 1940) is a high of 20.7°C and a low of 12.9°C, so today's high is 1.9°C cooler than that average.
How much has Ulsan warmed since 1940?
Comparing the first decade of the record (1940–1949) with the most recent (2016–2025), the annual mean temperature in Ulsan is about 2.7°C warmer.
How much does it rain in Ulsan?
Ulsan receives about 1,219 mm of precipitation per year on long-term average, with July typically the wettest month.
What is the average temperature in Ulsan?
Over the full record (since 1940), the annual mean temperature in Ulsan is about 14.6°C. The warmest month is August and the coolest is January.
What are the average temperatures in Ulsan by month?
Average daily highs and lows for each month in Ulsan (°C, full record since 1940): January 6°/−2°, February 8°/0°, March 13°/4°, April 18°/9°, May 23°/14°, June 25°/19°, July 29°/23°, August 30°/24°, September 26°/20°, October 21°/13°, November 15°/7°, December 9°/1°.
What is the weather like in Ulsan in summer?
June to August is summer in Ulsan, and it is wet and warm. It warms from 25°C by day and 19°C at night in June to 30°C and 24°C in August. Rain is steady at around 185 mm a month, spread over roughly 11 days. No season is wetter.
What is the weather like in Ulsan in winter?
December to February is winter in Ulsan, and it is cold. Daytime highs sit at 6–9°C and nights at −2 to 1°C; January is the coldest month. Rain picks up through the season: 3 rainy days and 27 mm in December, 4 days and 43 mm in February. No season is drier.
What is the weather like in Ulsan in spring?
Spring in Ulsan (March to May) is fairly mild. March starts at 13°C by day and 4°C at night; by May it is 23°C and 14°C. Rain is steady at around 90 mm a month, spread over roughly 7 days.
What is the weather like in Ulsan in autumn?
Autumn in Ulsan (September to November) is mild. September still brings 26°C afternoons and 20°C nights, November only 15°C and 7°C. Rain eases through the season: 10 rainy days and 174 mm in September, 4 days and 50 mm in November.
How many days a year does it rain in Ulsan?
On long-term average, Ulsan has about 80 days a year with at least 2 mm of rain or snow. The annual total is roughly 1,219 mm.

Weather in nearby cities