Jeju has a oceanic/humid subtropical climate, classified as Cfa in the Köppen system. The warmest month is August with an average high of 28°C, while the coldest month is January with lows dropping to 4°C. The annual temperature range of 24°C reflects moderate seasonal variation.
The driest month is October with only 7 rain days and 92mm of precipitation. For travellers, October through to the following month typically offers the best balance of warm temperatures and dry conditions. Average humidity ranges from 70% to 70% throughout the year.
Best Time to Visit Jeju
Based on temperature and rainfall data, the best months to visit Jeju are April, October, May. These months offer the most comfortable temperatures with relatively low rainfall, ideal for sightseeing and outdoor activities.
In August, Jeju experiences average highs of 28°C (82°F) and lows of 25°C (77°F). Expect around 17 rainy days and 10 hours of sunshine per day, with humidity averaging 70%. The 3°C gap between daytime and overnight temperatures is worth planning around: light layers work for most visitors during the day, but an overshirt or cardigan handles the cooler evenings. UV index averages 9, so sun protection is advisable on clear days.
Jeju typically sees 17 rainy days in August, with total precipitation of around 227mm. This is a notably wet period. A waterproof jacket or compact umbrella is essential, and it is worth building indoor alternatives into your daily itinerary for the inevitable rainy stretches. For context, the driest month in Jeju typically sees 4-6 fewer rain days than August.
Pack light layers, a light jacket for evenings, comfortable walking shoes, and sunscreen for Jeju in August. Daytime temperatures of 28°C are pleasant, but the evening drop to 25°C means a jacket is essential if you plan to be out after dark. With 17 rainy days, bring a compact umbrella or waterproof jacket for unexpected showers. Comfortable walking shoes are a priority given the amount of ground most visitors cover.
August is a reasonable time to visit Jeju. Expect 17 rainy days, so pack a light rain layer for flexibility. Average temperatures of 28°C make outdoor exploration comfortable during the dry periods. With 10 daily sunshine hours, there are reliable windows of good weather to plan outdoor activities around, even if the month is not the driest on the calendar.
The average high temperature in Jeju in August is 28°C (82°F), and the average low is 25°C (77°F). The mean daily temperature is approximately 27°C (80°F). The day-to-night range of 3°C is narrow, typical of coastal or maritime cities. These are 30-year climate normals based on the 1991 to 2020 reference period; individual years will vary, particularly in transitional months like spring and autumn.
The best month to visit Jeju is generally April. April offers the most sunshine at 9 hours per day and only 9 rainy days. Average temperatures reach 16°C, making it comfortable for sightseeing, outdoor dining, and exploring the city. If your travel dates are flexible, planning your trip around April gives you the best chance of dry, bright weather.
August is shoulder or low season in Jeju, meaning fewer tourists and generally lower prices than peak months. With 10 sunshine hours and 17 rainy days, the weather is less of a draw for mass tourism. This is an advantage for travellers who prefer a quieter, more relaxed experience with shorter queues and easier accommodation availability.
In August, Jeju suits a range of activities thanks to mild temperatures around 28°C. With frequent rain, indoor activities and covered attractions are a smart choice. Top options include exploring historic neighbourhoods, visiting museums and galleries, local food markets, and day trips to surrounding areas. With 10 hours of sunshine, parks and waterfront walks are particularly enjoyable.