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The story
El Niño — the ongoing pattern of above-average sea surface temperatures across the equatorial Pacific — is forecast to reach historic strength between fall and winter 2026.
On 5ch, users expressed confusion that despite El Niño years typically bringing cooler summers, hot days continued in western Japan and Tokyo this year, with some pointing to jet stream meandering as the cause.
El Niño continues to develop, and is forecast to reach historic strength in the latter half of 2026
El Niño is a phenomenon in which sea surface temperatures remain higher than average across a band of the equatorial Pacific stretching from near the International Date Line to the coast of South America, and it causes extreme weather worldwide, including in Japan.
El Niño conditions have persisted since spring 2026, and are forecast to reach historic strength from fall into winter.
Source: severe-weather.eu / Original article here
What people said
West Japan was hot again this year too
East Japan's been relatively mild. I mean, it's still hitting 30°C+ every single day, so it's a heatwave compared to Showa-era summers, but still
Why was West Japan so brutally hot?
Even in Tokyo there were a lot of days without "tropical nights" this year (nights that stay above 25°C) — almost felt cold
Feels like the Earth got an update and is behaving differently from the old patterns
That's not El Niño's fault — it's the jet stream meandering that's causing it
Still better than the last couple years though. The point is, even a "cool summer" is this hot now
Why not just drain the gas out of the South Kanto gas field and fill it with water instead?
Background and Key Points
El Niño refers to a periodic warming of surface waters across the equatorial Pacific, from around the International Date Line to the coast of South America; it’s tracked by agencies like Japan’s Meteorological Agency and NOAA because the shift in ocean heat reliably distorts atmospheric circulation worldwide. In Japan’s seasonal folklore, an El Niño year is supposed to mean a cool, rainy summer (Japan gets less of the Pacific High’s push) and a mild winter, a rule of thumb many older posters grew up hearing on the news. The current event has been building since spring 2026 and is forecast to peak at “historic” intensity by winter, meaning the textbook effects should, in theory, be more pronounced than usual this year.
What the thread actually disagreed about wasn’t whether El Niño is happening, but why the “cool summer” didn’t show up as expected: some posters blamed jet stream meandering (a wavier, more erratic polar jet that can trap heat domes over specific regions even during a cooling pattern) for western Japan’s brutal heat, while others pointed to eastern Japan feeling comparatively mild, with fewer nights failing to drop below 25°C, as evidence the pattern was working as advertised just regionally.
What’s easy to miss is that El Niño’s textbook effects are statistical tendencies, not guarantees, and they’re increasingly running on top of a warmer baseline climate — so the “cool summer” comparison itself is misleading when the reference point is decades of general warming rather than El Niño years alone. No one in the thread mentioned that Japan’s cool-summer/mild-winter association with El Niño is itself a simplification; the actual regional effects vary considerably by which ocean basin and jet stream configuration dominate in a given year.
*This article is excerpted and summarized from the 5ch (Science News+) thread “[Weather] El Niño continues to develop, forecast to reach historic strength in the latter half of 2026.”
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