So, it's been raining for a few days here in Jeju now, and 장마 season has officially begun. This year's start is a bit unusual — Korea's 장마 almost always begins in Jeju first, and this year it kicked off on June 30th, making it the third-latest start on record for the island. Only 1982 (July 5th) and 2021 (July 3rd) started later. Central Korea has had July starts before too, and this year's start there ranks as the seventh-latest on record.
As for right now: the Korea Meteorological Administration said the rain currently sitting over Jeolla and Gyeongnam, along with Jeju, was expected to ease off briefly through the afternoon of July 4th, then push into southern Chungcheong and southern Gyeongbuk overnight, with some spots around the capital region picking up light showers in the 5 to 20mm range. By the afternoon of July 5th, 장맛비 was expected to reach the capital region and inland Gangwon as well, with rain forecast to continue nationwide into early next week. Anyway, now that it's here, let's get into it.
장마 is the Korean monsoon season. The word is a compound of the hanja 장 ("long") and 마, a native Korean word for rain — so it literally means "long rain." But 장마 is never written with the hanja 長 in modern usage; even though the root is mixed, it's treated as a fully native word now.
The rain that falls during 장마 has its own name too: 장맛비 — 비 on its own just means rain. Notice the 시옷 in there. It's not 장마비, it's 장맛비. That's the 사이시옷 rule at work: when two words combine and the second starts with a plain consonant sound that gets reinforced in pronunciation, Korean inserts a ㅅ between them. Structurally it's 장마 + ㅅ + 비, and the spelling reflects that inserted ㅅ.
You'll also hear 장마 전선 a lot on the forecast — the "monsoon front," the actual meteorological boundary between hot air pushing up from the south and cooler air sitting over the peninsula. When that front stalls, Koreans call it 정체 ("stuck"), and that's the reason for a week straight of gray skies instead of one storm and done.
장마 isn't unique to Korea. It's a defining feature of East Asian summers more broadly, showing up in Japan and China too. That regularity is part of why 장마 sometimes gets called "the fifth season" here, as if it's its own entry on the calendar rather than just a rainy patch of summer. The front alone supplies over 30% of Korea's total annual rainfall, which is a big part of why rivers here swing so hard between wet and dry.
On average, 장마 runs 30 to 35 days, but it doesn't rain on all of them with actual rainfall happening on roughly 15 to 20 of those days, and of that, only 12 to 16 days trace back to the stationary front itself. The length and intensity vary a lot year to year, and climate change has been making that variance worse. 2020's 장마 dragged on into mid-August and set the record for longest on record, while the very next year, 2021's monsoon wrapped up in central Korea within a surprisingly short window.
The rain itself has its own vocabulary depending on intensity: a light, misty rain is 이슬비; a short, sudden burst is 소나기; and a heavy, prolonged downpour is 폭우 — the word news reports reach for once flood warnings start showing up.
Lately there's also been a shift toward 야행성 장마, "nocturnal monsoon," where the rain eases off during the day and comes down hard once night falls. 야행성 breaks down as 야 (night) + 행 (to move/act) + 성 (a suffix for "nature" or "tendency") — the same word used for nocturnal animals, just borrowed here to describe a monsoon that's active at night instead of during the day.
Then there's the stuff that comes with the rain rather than the rain itself. 습하다 means humid, and during 장마 it's not an exaggeration — bathroom mirrors fog up and laundry won't dry, and 곰팡이 (mold) becomes a real household enemy on top of that. A lot of people run a 제습기 (dehumidifier) nonstop and hang up little 제습제 packets in closets — 제습기 is the actual appliance, while 제습제 is the small pouch version.
Gear-wise, this is prime 우비 (raincoat) and 장화 (rain boots) season, though most people just carry a collapsible 우산 (umbrella) and call it a day unless the wind's bad enough to flip it inside out.
There's a food culture around all this too. Rainy days in Korea are strongly associated with 파전 (scallion pancake) and 막걸리 (rice wine), partly because the sound of rain hitting the ground apparently resembles the sizzle of pancake batter hitting a hot pan, at least that's the popular explanation, anyway.
One more term worth knowing: 마른장마, a "dry monsoon" — the years when the front barely produces rain. It sounds like good news, but it usually means drought concerns for farmers later in the summer, so weather reporters don't say it with much relief.