Jeju (Jeju Island) — sää kuukausittain

Jeju-forum threads on January weather agree it's the coldest month, crisp and chilly with a real chance of snow, though posters are quick to note the island rarely drops below freezing the way mainland Korea does this time of year - Seoul's winter is a different, harsher animal entirely. Wind is the recurring theme across threads, strong enough most days that it registers as the defining discomfort more than the raw temperature. Regulars call the occasional severe event genuinely rare rather than typical - one poster recalls a three-day blizzard that shut everything down, but stresses it was an outlier. The upside repeated across threads: crisp air, thin crowds, and volcanic coastal scenery some call more striking under grey winter skies than summer haze. The record: 9C days feeling like a raw 4C, 4.1C nights, 71mm across 10.4 days, 8.3cm of fresh snowfall, a 16.6C sea and wind averaging over 28 km/h - the windy, chilly month the forum describes.

Forum posters describe April as genuinely nice spring weather but real potential for chilly, windy and cloudy stretches - one mid-April visitor found Jeju warmer than Seoul but still windy enough, with wind chill, that it felt like only around 10C despite the nicer daytime numbers. Posters consistently recommend a proper jacket and sweater layered for both wind and the real chance of a cooler evening or a rainy patch. On the scenic side, posters name April specifically for the island's famous canola (rapeseed) flowers, which bloom throughout the month after spring flowers more broadly peak in late March - a real seasonal highlight layered on top of the generally mild, if variable, spring weather.

May is the month Jeju regulars choose over June: the weather is better, and the Korean summer holidays have not started, so the island is much quieter. Late May leans more towards summer than spring, warm and occasionally hot, and the qualification they always add is that this is a windy, foggy island - mornings and evenings can feel chilly even in a warm week, so a light jacket travels. Our row gives 22.5C days and 15.5C nights with a 20 kph wind. The thing to know before booking a beach holiday is that the beaches do not open until after mid-June; you can sunbathe in May, but the water is cold, our row putting it at 17.9C. The record: 9.3 precipitation days carrying 104.6mm, humidity 80 percent and 9.5 hours of sun.

Regulars are specific the real rainy season here usually doesn't start until the very end of this month, late May and early June instead typically bringing warm, not-too-hot days, though the water itself stays genuinely cold this early. Our row backs that warm, genuinely wet read, 25.7C reading as a hot 29C, over 20C nights feeling 22C, with a substantial 170.2mm of rain across 11 days and humidity at 87 percent. Regulars are consistent island weather here stays genuinely changeable day to day, constant strong winds a real factor that keeps conditions feeling cooler than the same heat would inland in Seoul. Evenings cool off noticeably even after a genuinely hot, humid day. The sea sits at a cool 21.9C. The record: 8.6 hours of sun, an 18.6 kph wind and AQI 68.

Jeju-forum threads comparing July to August sit July squarely inside the monsoon, or jangma, with one regular describing the rainy season as mainly a June event before warning newcomers to just prepare for warm, humid weather through July and August regardless. Early July is typically the wettest stretch, precipitation arriving in intense bursts rather than all-day drizzle - mornings tend to run clearer, afternoons stormier. The payoff for waiting: late July is called the sweet spot, when the monsoon often breaks and leaves the island lush and green between showers, the beaches warm and inviting. The record backs the intense-burst pattern: 30.1C days feeling like a sticky 36C, 25C nights, 169mm across 12.5 days, 87 percent humidity, 8.9 hours of sun and a 26.1C sea.

August on Jeju is hot and humid in a way the forum calls tropical, and hotter and more humid than the Korean mainland with it. The monsoon has usually finished by the end of July, so this is not daily rain - but heavy rain still comes, and a typhoon is a real August possibility rather than a remote one. The other August problem is company: mid-July to mid-August is the domestic peak, with most Korean workers taking their summer leave from late July into early August, and the standing advice is to book flights as far ahead as you can. The record: 31.4C days that feel like 37C, 26.2C nights, 12.8 precipitation days carrying 139.2mm, humidity 83 percent, a 29.4C sea and AQI 84.

Jeju's forum rates October highly — warm days, little rain, and Hallasan's autumn foliage typically at its best from the 10th to the 25th. Regulars note it cools quickly after sunset even in early October, so a light jacket or sweater for the evening is standard advice regardless of how warm the afternoon felt.