The Perfect Storm: How Record Heat in North Asia and a Blocked Strait of Hormuz Created a Textbook Energy Crisis

Record-Breaking Summer Heat Across North Asia

The summer of 2025 was historically extreme across Japan, South Korea, and China, setting multiple all-time records.

Japan recorded its highest temperature ever — 41.8°C (107.2°F) — in Isesaki, Gunma Prefecture, on August 5, 2025. This broke a new record set just days earlier when Tamba City hit 41.2°C on July 30 . Japan's June 2025 was the hottest on record, with national average temperatures 2.3°C above normal, and July 2025 became the hottest month ever recorded in the country's 127-year history .

South Korea endured an unprecedented number of “tropical nights” — nights where temperatures remain above 25°C. Seoul recorded 22 tropical nights in July 2025, breaking a 117-year record . The Korea Meteorological Administration confirmed that July 2025 was the hottest July since modern records began in 1973 .

China experienced its hottest summer on record in 2025, according to the China Meteorological Administration, with the national average temperature from June to August reaching 22.31°C, the highest since records began in 1961 . The World Meteorological Organization (WMO) confirmed that all three countries recorded extreme heat as a defining feature of 2025 .

Heat alerts and health impacts: Japanese authorities issued widespread heatstroke warnings, with Tokyo's medical examiner's office reporting 56 suspected heatstroke deaths between June and the end of July 2025 . South Korean officials advised residents to adopt protective measures as healthcare facilities came under strain, with more than 1,200 heat-related illnesses reported since May 15, 2025, including eight deaths .

The Geopolitical Shock: Strait of Hormuz Blockade

On February 28, 2026, the United States and Israel launched an air war against Iran. In retaliation, Iran's Islamic Revolutionary Guard Corps (IRGC) effectively blocked the Strait of Hormuz, forbidding passage of most commercial shipping . The strait is one of the world's most critical energy chokepoints, normally handling roughly 20% of the world's oil and LNG transport — approximately 20 million barrels of oil and oil-related products daily .

The disruption cascaded through global energy markets:

• Global LNG exports slumped to a six-month low by March 23, 2026, with the 10-day moving average for LNG shipments dropping about 20% since the start of March to roughly 1.1 million tonnes .
• Vortexa analysts warned that LNG shipments to Asia and Europe faced severe disruption, with no spare LNG capacity available to compensate for lost volumes. As Claire Jungman, who heads maritime risk and intelligence at Vortexa, stated: “With no extra capacity available in the LNG sector, any disruption could be both swift and substantial” .
• By April 2026, traffic through the Strait was nearly halted, compounded by a US naval blockade on Iranian ports. About 20% of global LNG supply originates from the U.S., but global rebalancing remained constrained .
• RBAC estimated that a protracted conflict would permanently disrupt virtually all Qatar LNG exports, as Qatar's entire fleet must transit the Strait. Combined LNG exports from Qatar and the UAE exceeded 80 million tonnes per annum in 2025, representing nearly 19% of global LNG trade .
• The Oxford Institute for Energy Studies documented that Iran's retaliatory strategy specifically targeted commercial shipping throughout the Gulf, not just military assets .

LNG Price Spikes and JKM Benchmark Impacts

The convergence of heat-driven demand and supply disruption sent the benchmark Japan Korea Marker (JKM) — the price reference for LNG delivered to Northeast Asia — sharply higher at two distinct points.

Summer 2025 heatwave-driven spike: In July 2025, Platts JKM rose to $12.758/MMBtu on July 11, supported by surging demand due to heatwaves across North Asia. S&P Global noted that prices were “expected to stay firm” as the heatwave and early supply uncertainty pushed the August JKM contract to $12.942/MMBtu on July 10, the highest level since early 2025 .

Post-blockade spike: After the Strait of Hormuz closure, spot prices rose sharply. By July 6, 2026, JKM was at $16.07/MMBtu — still 22.68% higher year-on-year, having fallen about 15% from earlier crisis peaks in March–April 2026 . The CFR report (July 23, 2026) listed the Hormuz closure as one of the most consequential conflict-driven chokepoint disruptions in modern history .

Emergency Reserve Responses and Supply Timeline

Japan and South Korea, both heavily dependent on LNG imports for power generation, activated strategic fuel reserves and issued emergency conservation appeals during the peak summer months of 2025 and again during the 2026 supply crunch. The combination of record heat-driven demand and blocked Hormuz shipping left these economies with minimal spare capacity — Vortexa explicitly noted that “with no extra capacity available in the LNG market, any loss of supply from the Gulf will be extremely difficult to replace” .

Key Event Timeline

Why the Convergence Was So Dangerous

This was not a hypothetical scenario but a documented, compounding crisis. The IMF and CFR assessed the Strait of Hormuz closure as among the most severe conflict-driven chokepoint disruptions in modern history, with Asia's fuel-importing economies bearing the heaviest exposure .

The core dynamic was simple and devastating: record-breaking summer heat (Japan's 41.8°C, South Korea's 22 tropical nights, China's hottest summer ever) drove surge demand for LNG for power generation precisely as the Strait of Hormuz blockade removed ~20% of global LNG supply from the market. With no spare production capacity available globally to replace the lost Qatari and UAE volumes, prices remained elevated and strategic reserves were drawn down .

For Japan and South Korea in particular, the crisis exposed the vulnerability of economies that rely on imported LNG for a significant share of electricity generation. The dual shock of heatwave-driven demand and geopolitical supply disruption left policymakers with few options beyond conservation appeals and reserve releases — a textbook energy crisis made more severe by its compound nature.