Jeju City weather in September

September is a fair month to visit Jeju City: highs of 25°C (76°F) and about 185 mm (7.3 in) of rain on average. Nights average 23°C (73°F) and cloud cover 68% (NASA POWER, 2001–2025 averages). The sea averages 29°C (85°F). It is the 4th wettest month of the year and the 3rd warmest. Compared with August, it is cooler and drier; October brings highs of 20°C (69°F) and 89 mm (3.5 in) of rain.

Is September a good time to visit Jeju City?

fair month Weather score 56/100.

September is a fair month in Jeju City. The weather is usually best in Oct.

See Jeju City's sky and forecast now

Does it rain a lot in Jeju City in September?

Yes, it is one of the rainy months: about 185 mm (7.3 in) falls in an average September. It is the 4th wettest month of the year.

How warm is Jeju City in September?

Days average 25°C (76°F) and nights 23°C (73°F).

Jeju City weather by month

Month	High	Low	Rain	Cloud	Sea	Weather
January	9°C (48°F)	6°C (43°F)	50 mm	78%	16°C (60°F)	least pleasant
February	9°C (49°F)	7°C (44°F)	66 mm	74%	14°C (58°F)	least pleasant
March	11°C (53°F)	8°C (47°F)	90 mm	69%	14°C (56°F)	least pleasant
April	15°C (58°F)	12°C (53°F)	137 mm	70%	15°C (59°F)	least pleasant
May	18°C (64°F)	15°C (60°F)	141 mm	73%	17°C (63°F)	fair
June	22°C (71°F)	20°C (67°F)	192 mm	81%	22°C (71°F)	fair
July	26°C (78°F)	24°C (75°F)	240 mm	74%	27°C (80°F)	least pleasant
August	28°C (82°F)	26°C (79°F)	261 mm	67%	30°C (87°F)	least pleasant
September	25°C (76°F)	23°C (73°F)	185 mm	68%	29°C (85°F)	fair
October	20°C (69°F)	18°C (65°F)	89 mm	59%	26°C (79°F)	best
November	16°C (60°F)	13°C (56°F)	72 mm	66%	22°C (71°F)	fair
December	11°C (52°F)	8°C (47°F)	56 mm	77%	18°C (65°F)	least pleasant

Sources: 2001–2025 monthly averages from NASA POWER (MERRA-2 reanalysis), sea temperature from Open-Meteo Marine. Page updated Oct 31, 2026. How we rate months