Seoul May 11 High Temperature: Will It Hit Twenty Degrees?

Seoul’s weather on May 11 has already been priced as a foregone conclusion. The 20°C outcome sits at 97% on Polymarket, and the momentum behind that number is not subtle. In the past 24 hours, the contract surged 58.5 percentage points, which is one of the sharpest single-day repricing events you see in a short-duration weather market. The market is not pricing uncertainty here. The market has made a call.

This contract asks one question: what is the highest temperature recorded in Seoul on May 11, 2026? The 20°C outcome, priced at $0.97, commands nearly all the probability. Every competing outcome, including 21°C, 22°C or higher, and every outcome below 19°C, splits the remaining 3%. Here’s what the measurements are telling us: Seoul’s mid-May climatology, combined with the current synoptic pattern over the Korean Peninsula, has pointed forecasters squarely at a peak daily high near 20°C.

How the Contract Resolves

Resolution is straightforward. The contract settles at 2026-05-11 12:00:00 UTC. The resolution source is the official maximum temperature reading for Seoul on that date. The 20°C bracket wins if Seoul’s peak high on May 11 lands in the 20°C range, typically 20.0°C to 20.9°C depending on bracket definitions. Any reading outside that window shifts value to adjacent contracts.

• 20°C (YES): $0.97, implied probability 97%. This outcome requires Seoul’s daily maximum to land squarely in the 20°C bracket on May 11.
• All other outcomes combined: $0.03, implied probability 3%. This covers 21°C, 22°C or higher, 19°C, 18°C, and every bracket down to 12°C or below.

The path to a non-20°C resolution is narrow but real. A stronger-than-forecast warm advection event pushing Seoul above 21°C would drain value from the 20°C contract and redistribute it upward. Conversely, a cold front arriving earlier than models suggest could push the daily maximum below 19°C. Neither scenario is what current numerical weather prediction models show for the Korean Peninsula on May 11, which is why the market has converged this sharply.

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Momentum and Market Signals

The momentum composite here is unambiguous. A 58.5% jump in 24 hours, zero movement in the last hour, and a trend score of 63.53 together indicate that the market received a decisive signal and then stopped moving. That pattern typically reflects updated numerical weather prediction guidance, likely a model run from May 9 or May 10 that tightened the forecast cone around the 20°C bracket. The market absorbed the signal, repriced sharply, and has since stabilized.

Total volume stands at $138,711, with $119,082 of that changing hands in the last 24 hours. Liquidity sits at $7,103. That liquidity number is thin. A single large trade could move this price meaningfully in either direction before resolution. Traders watching this contract should understand that the 97% price reflects current consensus, but thin liquidity means any surprise, including an unexpected late-model shift, could reprice the contract quickly.

• The 24h price change of +58.5% is the dominant signal. It dwarfs the 1h reading of +0.0%, which means the repricing event is complete for now.
• Volume concentration is extreme. Nearly 86% of total volume moved in the last 24 hours, confirming this was a single catalyst event rather than gradual accumulation.
• Liquidity at $7,103 is below the threshold for high-confidence price stability. New weather data or a model update before 2026-05-11 12:00:00 could shift the price sharply.
• Open interest is zero. No positions remain unresolved from prior periods. All capital is freshly committed.

Lines Analysis: Seoul Temperature on May 11

The 97% probability reflects a tight meteorological consensus. South Korea’s Korea Meteorological Administration and global models including the European Centre for Medium-Range Weather Forecasts both typically show mid-May Seoul temperatures in the 18°C to 22°C range. A forecast pinned at 20°C on May 11 is climatologically unremarkable, which is exactly why the market is comfortable sitting at 97%. The data doesn’t care about the politics, and in this case, the data is pointing at a perfectly ordinary spring day in Seoul.

The genuine risk lives at the edges of the distribution. Seoul’s May temperature is sensitive to the position of the Siberian High and the strength of southwesterly flow off the Yellow Sea. If the warm flow strengthens ahead of schedule, the 21°C or 22°C+ contracts absorb value. If a cold trough digs deeper than models show, the 19°C or lower brackets become relevant. At current model consensus, neither scenario carries significant probability, but the resolution window closes at 2026-05-11 12:00:00 UTC, and weather forecasts carry irreducible error at 24 to 48 hours.

• Korea Meteorological Administration’s operational forecast for May 11 is the single most important input. Any update showing a high above 21°C or below 19°C would move adjacent contracts immediately.
• ECMWF ensemble guidance for the Korean Peninsula on May 11 will show spread across the distribution. Tight ensemble spread reinforces the 97% price.
• A late-breaking cold front over northeastern China moving faster than forecast is the primary bearish risk for the 20°C contract.
• Strengthening southwesterly flow from a deepening surface low in the Yellow Sea is the primary upside risk, potentially pushing Seoul into the 21°C range.

The $138,711 in total volume is meaningful for a short-duration weather contract. The market has committed real capital to the 20°C outcome, and the data supports that commitment. What the market cannot price perfectly is the last 12 to 24 hours of model evolution before resolution.

LINES VERDICT

Seoul Locks In at Twenty Degrees

Current meteorological consensus aligns tightly with the 20°C outcome, and the market’s repricing event appears to have fully absorbed the latest forecast guidance. The thin liquidity means any model shift before resolution could create a short window of mispricing.

What the market says: 97% probability translates to near-certainty in prediction market terms. The contract has essentially resolved in traders’ minds. The only remaining variable is whether Seoul’s actual maximum reading on May 11 stays inside the 20°C bracket before the 2026-05-11 12:00:00 UTC close.

Key unknown: The final Korea Meteorological Administration forecast update for May 11, issued in the hours before resolution, is the single data point that could reprice this contract. Any reading in updated guidance that pushes the expected high above 20.9°C or below 20.0°C would shift probability to adjacent brackets.

Scientific Context

Seoul’s mean daily maximum temperature in mid-May sits in the 19°C to 22°C range historically. The city sits at roughly 37.5°N latitude, where spring warming is well underway by the second week of May but summer heat has not yet established. A 20°C high on May 11 is not unusual. It is close to the climatological average for the date, which is precisely why the market converged here rather than at an extreme bracket. The broader market context, including the related market showing 56% probability that 2026 ranks among the hottest years on record globally, suggests the current year’s background warmth is real. That said, a single station’s daily maximum is far more sensitive to local synoptic conditions than to global temperature anomalies. Here, local forecasting skill dominates the resolution outcome.

Frequently Asked Questions

• What does 97% probability mean for this contract? It means Polymarket traders have collectively placed 97% of the money on the 20°C outcome. It reflects market consensus, not a meteorological guarantee.
• What does the non-20°C side pay out on? Any outcome other than a 20°C daily maximum in Seoul on May 11 wins the 3% contracts. That includes outcomes above 20°C and below 20°C.
• What single event would move this price before resolution? An updated Korea Meteorological Administration or ECMWF forecast showing Seoul’s May 11 high shifting outside the 20°C bracket would immediately reprice adjacent contracts.
• When does this contract resolve? Resolution occurs at 2026-05-11 12:00:00 UTC, based on the official maximum temperature recorded for Seoul on May 11.
• Is the volume reliable enough to trust the price? Total volume of $138,711 with $7,103 in liquidity is thin. The price can move sharply on a single trade or a new forecast update before resolution.

This analysis reflects market conditions as of 2026-05-10 22:10:29. Prediction market probabilities are volatile and shift as new data and regulatory decisions emerge, especially as the 2026-05-11 12:00:00 resolution date approaches. Lines.com does not accept bets or provide financial or gambling advice. All market outcomes are uncertain.