How El Niño Affects South Korea: Changma, Typhoons, and Winter Anomalies
Published: July 26, 2026 · 9 min read
TL;DR — Korea at the Edge of the El Niño Teleconnection
South Korea sits at the boundary of El Niño's main teleconnection zones, which means its impacts are weaker and more variable than for countries closer to the tropical Pacific. The primary effects are: reduced summer monsoon rainfall (changma) by 10-20%, fewer but potentially more intense typhoon landfalls, and warmer-than-normal winters of 1-2 degrees Celsius. The 2026-27 very strong El Niño forecast tilts the odds toward a drier-than-normal 2027 monsoon season following the event's winter peak.
The Changma Monsoon Connection
The Korean summer monsoon (changma) typically arrives in late June and persists through late July, delivering roughly 50-60% of South Korea's annual precipitation. El Niño affects changma by altering the position of the western North Pacific subtropical high — a semi-permanent high-pressure system that steers the monsoon rain band.
During El Niño summers, the subtropical high tends to be weaker and displaced eastward. The monsoon rain band shifts south and east, reducing rainfall over the Korean Peninsula. The Korea Meteorological Administration (KMA) analyzed six strong El Niño events since 1970 and found that June-August rainfall averaged 12% below normal, with the largest deficits in July — the core of the changma.
The effect is not uniform. The 2015-16 El Niño produced Seoul's second-driest July since 1973, with only 56mm of rain compared to the normal 394mm. But the 1997-98 El Niño had near-normal changma rainfall. The determining factor appears to be the Indian Ocean Dipole (IOD): when a positive IOD co-occurs with El Niño — as it did in 2015 — the drying effect on Korea is amplified. The July 2026 IOD index is trending positive, suggesting the 2026-27 event may follow the 2015-16 rainfall pattern.
Typhoon Track Shifts
El Niño alters the steering currents that guide western Pacific typhoons. During El Niño, the subtropical ridge weakens and retreats eastward. Typhoons that form in the western Pacific encounter an earlier recurvature point — instead of tracking straight toward the Korean Peninsula, they curve northeast toward Japan earlier in their lifecycle.
The statistics bear this out. KMA typhoon landfall data from 1951-2022 shows that Korea averages 1.2 typhoon landfalls per year during El Niño seasons, compared to 2.1 during La Niña and 1.7 during neutral years. But the typhoons that do make landfall during El Niño tend to be more intense — their average central pressure at landfall is 5-8 hPa lower, corresponding to roughly 10-15% stronger winds. This is because El Niño-warmed waters in the central Pacific give typhoons a longer track over high ocean heat content before reaching Korea.
For 2026-27, the reduced typhoon frequency is likely good news for Korean coastal communities. But the intensity risk means any typhoon that does approach the peninsula should be taken seriously. Typhoon Chaba in October 2016, which struck Busan with 175 km/h winds, occurred during a neutral ENSO phase, but its rapid intensification was enabled by the residual warm pool from the 2015-16 El Niño. The 2026-27 event could leave a similar warm wake in the western Pacific that persists into the 2027 typhoon season.
Winter Temperature Anomalies
South Korea's winter temperature response to El Niño is moderate but consistent. KMA data shows that December-February temperatures during strong El Niño events average 1.0-1.5 degrees Celsius above the 1981-2010 baseline. The warming is stronger in the southern half of the peninsula — Busan and the Gyeongsang provinces — than in northern regions like Seoul and Gangwon Province.
Jeju Island is a special case. Its maritime climate makes it more sensitive to Pacific Ocean temperature changes than the mainland. Jeju's winter temperatures during strong El Niños average 2.0 degrees Celsius above normal — enough to significantly reduce the island's mandarin orange frost risk, which is a major economic factor for Jeju agriculture. The 2015-16 winter saw Jeju's tangerine orchards lose only 2% of crop to frost, compared to 15% in the preceding La Niña winter of 2014-15. Jeju produces roughly 600,000 tons of citrus annually, accounting for over 30% of Korea's fruit production by value, so a 13-percentage-point swing in frost loss translates to tens of millions of dollars in saved crop value.
The physical mechanism is indirect but well-established. El Niño warms the Kuroshio Current, which carries warm water from the western tropical Pacific northward past Japan and into the waters surrounding Korea. The warm Kuroshio raises sea surface temperatures in the Korea Strait and East China Sea by 0.5-1.5 degrees Celsius during El Niño winters. This moderates coastal air temperatures, with the effect strongest in December and January, before the Siberian High fully establishes its dominance over the peninsula.
Agriculture and Water Resources
South Korea's agricultural sensitivity to El Niño centers on water availability for rice irrigation. Rice paddy cultivation requires roughly 2,000mm of water per growing season, with most supplied by monsoon rainfall captured in agricultural reservoirs. When the monsoon underperforms — as in El Niño summers — reservoir levels in August and September, which coincide with the critical rice grain-filling period, can drop below irrigation demand.
The Korea Rural Community Corporation manages approximately 3,400 agricultural reservoirs nationwide. During the 2015-16 El Niño, 240 reservoirs in Chungcheong and Gyeonggi provinces dropped below 30% of capacity by August, triggering water rationing for rice irrigation. The affected area covered roughly 45,000 hectares, producing an estimated 200,000-ton reduction in rice output — approximately 5% of South Korea's annual production of 4 million tons.
Rice accounts for roughly 40% of Korean agricultural output by value, but the country maintains near-total self-sufficiency in rice (over 95%). This means production shortfalls directly affect farmers' incomes rather than consumer prices — the government's rice purchase program historically absorbs surplus and deficit through buffer stocks. However, the fiscal cost rises during El Niño drought years. The 2015-16 El Niño cost the Korean government an estimated 180 billion won ($135 million) in additional rice price support and irrigation subsidies.
Beyond rice, Korean fruit production shows a mixed El Niño response. Winter warming during El Niño can advance the flowering of apple and pear trees by 1-2 weeks, which increases vulnerability to late frost damage if a cold snap follows the early bloom. Andong and Yeongju, the main apple-growing regions, experienced this pattern in 2016 when a March cold spell damaged roughly 8% of early-flowering trees. The 2026-27 El Niño winter is likely to replicate this pattern, and orchard managers in Gyeongbuk Province are advised to maintain frost protection measures even as winter temperatures run above normal.
For the broader East Asian context, see How El Niño Affects Global Weather and El Niño in Southeast Asia: Vietnam and Thailand. For the 2026-27 forecast timeline, see El Niño 2026: What to Expect.
