Climate and monthly weather forecast
Jeju, South Korea

A high sunrise Panorama of the Jeju Island in Jeju, South Korea
A high sunrise Panorama of the Jeju Island in Jeju, South Korea

The climate of Jeju

Jeju, an island city in South Korea, imbibes climatic conditions typical of a humid subtropical region with no dry season. This rearranges itself into a Köppen climate classification of Cfa, sealing its reputation as a city where temperatures differ widely throughout the year. Geographically, Jeju graces the Korea Strait’s waters, taking in the effects of the sea's close proximity.

Monthly averages of climatological data precisely reveal these wide differences. The maximum temperature in Jeju sporadically fluctuates around the year, springing from a palatable 8.3°C (46.9°F) in January to its highest veil of 29.8°C (85.6°F) in July. The journey from cool to a sweltering climate unveils itself in an exciting zig-zag pattern. The minimum temperatures follow the same route, starting from 3.2°C (37.8°F) in January and peaking at 24.3°C (75.7°F) in August.

The pattern of humidity reveals a unique trend. Starting from display of 65.3% relative humidity in January, it scales up to a maximum of 78.3% in July before winding down back to 65.1% in December. The mini-climaxes in humidity levels around mid-year are sporadically followed by descents, making the humidity range inconsistent and fascinating at the same time.

While analysing the rainfall data, a noticeable pattern surfaces. The absence of a dry season reflects in the consistent presence of rainfall throughout the year. The data exposes two peaks - the first one in July with a massive 240mm (9.45") and dares to challenge itself with a second, more pronounced peak of 263mm (10.35") in August. This pattern synchronises harmoniously with the increased level of humidity during these months.

Even the number of daylight hovers unassumingly from a low of 10 hours in January to a high of 14.4 hours in June. A sharp descent follows, tapering off at 10 hours again by December. The pattern of viewing hours apes that of the number of daylight hours, reaching a maximum of 6.5 hours in April.

These unique weather changes underline the distinct features and characteristics of Jeju's climatic cycle, converting it into a weather enthusiast's paradise.

The best time to visit Jeju

The optimal time to visit Jeju seems to be between April and June. This period microscopically experiences relative temperatures from a high point of 17.5°C (63.5°F) to 24.8°C (76.6°F) and from a lower range of 10.2°C (50.4°F) to 18.7°C (65.7°F). The humidity stays within manageable bands, and the rainfall, though present, is less pronounced. Notably, the daylight goes beyond the 13-hour mark during this period, wrapping up to 14.4 hours in June. Sunshine hours peak at a phenomenal 6.8 hours a day on average in May, ensuring that visitors can enjoy outdoor activities.

The worst time to visit Jeju

It appears that July and August form the least hospitable part of the year to visit Jeju. This time intuitively coincides with the maximum temperature crossing the 29°C (84.2°F) mark. Humidity levels hike up to 78.3% in July and 76.5% in August. Rainfall records its annual peaks, with a high of 240mm (9.45") in July and reaching its zenith in August at 263mm (10.35"). The frequent rainfall and high humidity contribute to a muggy climate, discouraging numerous outdoor activities.

Spring weather in Jeju

Spring dancingly glides into Jeju from March to May. Here, temperature patterns tiptoe their ascent, with highs escalating from 12.8°C (55°F) to 21.6°C (70.9°F) and lows from 6.1°C (43°F) to 14.4°C (57.9°F). While rainfall preserves its consistent presence, the amount stays within the manageable region of 89mm (3.5") to 96mm (3.78"). The daylight hours lace up to 13 hours a day, peaking at 13.9 hours in May.

Summer weather in Jeju

Summer, sweeping in from June to August, introduces sweltering temperatures and heavy rainfall into Jeju's climate pattern. The hotter climate nudges temperature highs to the 29°C (84.2°F) mark and the lows to above 23°C (73.4°F). Rainfall joyously bounces from 181mm (7.13") in June to a whopping 263mm (10.35") in August. The daylight hours, ironically, start their downward journey, reducing from 14.4 hours to 13.4 hours towards the end of the summer.

Autumn weather in Jeju

Autumn, occupying September to November, witnesses a gradual calming down of temperatures. High temperatures organically reduce from 25.8°C (78.4°F) to 16°C (60.8°F), and the minimums decline from 20.4°C (68.7°F) to 9.8°C (49.6°F). Rainfall amounts follow the same path, with a substantial decrease from 222mm (8.74") in September, downsizing to 62mm (2.44") in November. The daylight hours shrink, starting at 12.4 hours in September and gradually waning to 10.4 hours in November.

Winter weather in Jeju

Winter weaves itself around Jeju from December to February. This period eerily resonates with a marked reduction in temperatures. The highs suffer to the 9°C (48.2°F) level, and the lows dig down to the 3°C (37.4°F) to 5°C (41°F) region. Rainfall stays within comfort at around 50mm (1.97") to 60mm (2.36") range, while the daylight hours shorten to around 10 hours a day. Winter even shrouds the island's sunshine, limiting it to less than 3 hours a day on average.

Weather in January

The transition from winter to spring in Jeju, South Korea, starts with January, best known for its chilly temperatures with highs of 8.3°C (46.9°F) and lows dipping to 3.2°C (37.8°F). The month is considered cold, yet precipitation is relatively moderate in the form of scattered showers and possibly snow, keeping the island's vegetation lush. Weather in January »

Weather in February

In Jeju, February brings mild but chilly temps despite being slightly warmer than the preceding month. With highs reaching 9.4°C (48.9°F), the island remains cold throughout the month. February holds a charm as the island becomes a host to a plethora of snowdrops, signaling the departure of winter. Weather in February »

Weather in March

March ushers in milder weather, a transition phase between winter and spring in Jeju. With daily highs reaching 12.8°C (55°F), the month showcases a gradual increase in temperatures as the heavy winter coats start to give way to lighter attire. Weather in March »

Weather in April

April in Jeju brings a striking transformation as the island brightens up with temperatures reaching a pleasant high of 17.5°C (63.5°F). Spreading warmth across the island, April showcases a spring at its peak with all things beautiful proliferating around. Weather in April »

Weather in May

May in Jeju witnesses a marked advancement of spring, turning into early summer with highs around 21.6°C (70.9°F). The month signifies a warmth that permeates not just the weather but also the island's vibrant life. Sights of emerald-green tea fields and lush vegetation dominate, symbolizing the island in full bloom. Weather in May »

Weather in June

June in Jeju marks the onset of summer, with temperatures soaring up to 24.8°C (76.6°F). The month sees a perceptible change in the island's ambiance, notably with longer daylight hours. As the ocean gets warmer, the beach season officially commences, attracting swimmers, surfers, and sunbathers. Weather in June »

Weather in July

With temperatures peaking to 29°C (84.2°F), July is the hottest month in Jeju, marking the zenith of summer. The abundant sunshine illuminates the crystal-clear waters surrounding the island, their warmth inviting for various water activities. Weather in July »

Weather in August

August continues the narrative of a warm, wet summer in Jeju. With the mercury hitting a high of 29.8°C (85.6°F), the weather remains hot but slightly less severe than July. As sea temperatures rise, opportunities for snorkeling, diving, and swimming multiply, adding to Jeju's summer euphoria. Weather in August »

Weather in September

The tingling heat of summer begins to wane in September in Jeju, with temps peaking at 25.8°C (78.4°F). As the month progresses, the searing heat gives way to milder conditions, setting in a pre-autumn ambiance. While the beginning of September still retains the summer vibrancy, the latter half witnesses the autumnal transformation of the verdant landscapes into stunning palettes of yellow and orange. Weather in September »

Weather in October

October manifests the quintessential autumn in Jeju and comes with a noticeable drop in temperatures, which offer relief after the sweltering summer months. The month brings a refreshing feel, a blend of mild sunny days and nippy evenings. Weather in October »

Weather in November

November signals the onset of winter in Jeju as temperatures drop further, recording highs of only 16°C (60.8°F). With the majority of foliage shed, the landscapes take on a different aura, alluding to the approaching cold season. Weather in November »

Weather in December

December comes with freezing winds and cold weather, registering lows of 5.3°C (41.5°F) in Jeju. Marking the peak of winter, snowfall periodically blankets the island, turning it into a striking white canvas. The usual hustle of outdoor activities slows down, shifting focus to indoor engagements and hot springs. Weather in December »

Frequently asked questions

What part of the year is the coldest?

January tends to be the coldest month, with temperatures averaging a daily high of 8.3°C (46.9°F) and a low of 3.2°C (37.8°F).

How many days does it rain?

Throughout the year, there are 130.2 rainfall days, and 1498mm (58.98") of precipitation is accumulated.

What is the month with the least sunshine?

With an average of 2.3h of sunshine, January has the least sunshine of the year in Jeju.

What are the months with the lowest UV index in Jeju?

January and December, with an average maximum UV index of 3, are months with the lowest UV index in Jeju, South Korea.

What is the least humid month?

February and March, with an average relative humidity of 64.9%, are the least humid months.

What month is the sea coldest?

With an average sea temperature of 13.3°C (55.9°F), March is the month with the coldest seawater.

What month has the most sunshine?

With an average of 6.8h of sunshine, May has the most sunshine of the year.

When are the longest days?

June has the longest days of the year, with an average of 14h and 18min of daylight.

What is the most humid month?

The most humid month is July, with an average relative humidity of 78.3%.

What is the month with the highest UV index?

July is the month with the highest UV index, with an average maximum UV index of 11.

What is the hottest time of year in Jeju?

The warmest time of the year is August, with temperatures averaging a high of 29.8°C (85.6°F) and a low of 24.3°C (75.7°F).

What is the rainiest month?

August is the month with the most rainfall. Rain falls for 13.5 days and accumulates 263mm (10.35") of precipitation.

What is the month with the warmest sea water?

The month with the warmest seawater is August, with an average sea temperature of 26.2°C (79.2°F).

What is the driest month?

The month with the least rainfall is December, when the rain falls for 10.8 days and typically collects 48mm (1.89") of precipitation.

What is the month with the shortest days?

The month with the shortest days is December, with an average of 10h and 0min of daylight.

Is there Daylight Saving Time (DST)?

Jeju does not observe Daylight Saving Time (DST). KST timezone is used throughout the entire year.

Average temperature
Jeju, South Korea

Average temperature - Jeju, South Korea

The warmest month (with the highest average high temperature) is August (29.8°C).
The month with the lowest average high temperature is January (8.3°C).

The month with the highest average low temperature is August (24.3°C).
The coldest month (with the lowest average low temperature) is January (3.2°C).

Average humidity
Jeju, South Korea

Average humidity - Jeju, South Korea

The month with the highest relative humidity is July (78.3%).
The months with the lowest relative humidity are February and March (64.9%).

Average rainfall
Jeju, South Korea

Average rainfall - Jeju, South Korea

The wettest month (with the highest rainfall) is August (262.5mm).
The driest month (with the least rainfall) is December (47.7mm).

Average rainfall days
Jeju, South Korea

Average rainfall days - Jeju, South Korea

The month with the highest number of rainy days is August (13.5 days).
The month with the least rainy days is October (7 days).

Average sea temperature
Jeju, South Korea

Average sea temperature - Jeju, South Korea

The best month for swimming (with the highest average sea temperature) is August (26.2°C).
The coldest month (with the lowest average sea temperature) is March (13.3°C).

Average daylight / Average sunshine
Jeju, South Korea

Average daylight / Average sunshine - Jeju, South Korea

The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).

The month with the most sunshine is May (Average sunshine: 6h and 48min).
The month with the least sunshine is January (Average sunshine: 2h and 18min).

Jeju, South Korea

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