Seoul May 19 High Temp: Will It Hit Twenty-Five?

Seoul’s weather on May 19 comes down to a single degree. The market gives a 26% chance that the daily high lands exactly at 25°C, while the remaining 74% is spread across every other outcome, from 18°C or below to 28°C or higher. That kind of fragmented probability structure tells you something important: this is not a YES-versus-NO bet on whether it will be warm. It is a precision bet on a specific one-degree band in a city where late May temperatures swing routinely between 20°C and 28°C.

With resolution locked to 2026-05-19 12:00:00 and total market volume sitting at $21,371, the contract is thin. The 24-hour volume of $21,101 represents nearly all trading on record, which means almost every dollar in this market changed hands in the last day. Liquidity at $59,564 is real but narrow. One well-timed weather forecast revision could move this price sharply before the window closes.

How the Twenty-Five Degree Contract Works

This contract resolves YES if Seoul’s official highest temperature on May 19 reaches exactly 25°C. The resolution source is Polymarket’s market resolution mechanism, which draws on official meteorological observation data for Seoul. Outcome bands are spaced one degree apart across the full distribution, so a reading of 24.9°C or 25.1°C would resolve a different contract entirely.

• YES (25°C highest temp): priced at $0.26, implying a 26% probability
• NO (any other outcome): priced at $0.74, implying a 74% probability

The 74% NO side wins whenever Seoul’s recorded high on May 19 lands outside the 25°C band. Seoul’s Korea Meteorological Administration records peak daily temperatures to a single decimal. A 26°C reading, a 24°C reading, or anything above 28°C all resolve this specific contract as NO. The Korea Meteorological Administration’s automated surface observation network provides the data feed that underpins resolution, and that agency has a strong track record of same-day reporting.

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Momentum and Market Conviction

The combined momentum signal here is flat. The 1-hour change is zero, the 24-hour change is unavailable, and the trend score sits at 33.33 out of 100. That composite reads as a market that priced up quickly on initial trading and then stopped moving. The most likely driver is a short-term forecast update: someone modeled the May 19 Seoul high, placed a concentrated bet, and the market has been quiet since.

Volume context matters here. Total market volume is $21,371, with $21,101 coming in the last 24 hours. Liquidity is $59,564. Both figures are well below the $1 million threshold that would indicate broad trader participation. This is a low-liquidity market. A single new bet of a few thousand dollars could reprice the contract by several percentage points. Treat the 26% figure as directionally useful, not as a precise probability estimate.

Key Factors

• The 26% YES price reflects market consensus that a 25°C high is the single most likely outcome, but fragmentation across a dozen bands keeps any individual band below 30%.
• Seoul’s late May climatological average high is approximately 23°C to 24°C, which places 25°C at the warm edge of the normal range for this date.
• The 1-hour price change of +0.0% and the unavailable 24-hour reading together suggest no new forecast information has entered the market since initial trading.
• The trend score of 33.33 indicates below-average conviction, consistent with a weather market that is waiting on the final 24-hour forecast window.
• Thin liquidity means the market is pricing uncertainty about a single meteorological measurement, not a structural view on Seoul’s climate.

Lines Analysis: Seoul Temperature on May 19

The Korea Meteorological Administration’s short-range forecast models are most reliable within 48 hours of a target date. As of 2026-05-18, Seoul sits inside that window. May 2026 has shown a pattern of slightly above-normal temperatures across the Korean Peninsula, consistent with the broader Northeast Asia warming trend that has pushed spring highs up by roughly 0.5°C to 1.0°C relative to the 1991-2020 baseline. That background warming nudges the probability distribution slightly toward the 24°C to 26°C range rather than cooler outcomes.

The NO side benefits from dispersion. Even if the market’s implicit forecast is a 25°C high, Seoul’s actual observation could land at 24°C or 26°C with nearly equal probability. The Korea Meteorological Administration’s surface stations report to 0.1°C precision, and day-of wind shifts or cloud cover changes routinely push final readings one degree off model output. Missing the 25°C band by one degree in either direction resolves this contract NO and pays out the 74% side.

Signals to Monitor

• Korea Meteorological Administration’s 24-hour forecast update for Seoul on the morning of May 19 will be the most direct signal: a predicted high of 25°C to 26°C would support YES, while a forecast of 23°C to 24°C would pressure the price downward.
• Any synoptic-scale weather system moving through the Yellow Sea before May 19 could suppress or enhance Seoul’s daytime high by 2°C to 3°C, which would decisively shift probability away from the 25°C band.
• The thin liquidity at $59,564 means a single large trader acting on an updated private forecast could move the contract price by 5 to 10 percentage points before resolution.
• Regional temperature anomaly data from the Korea Meteorological Administration’s daily bulletins, if released before resolution, would provide the most reliable calibration point for this contract.

At $21,371 in total volume, the market is light enough that price discovery is incomplete. The data currently favors a modest probability for 25°C, consistent with the warm edge of Seoul’s late May normal range. But the NO side holds structural advantage simply because the temperature distribution is spread across more than ten possible outcomes, and landing precisely on 25°C requires both the forecast and the observation to align within a single degree.

LINES VERDICT

Outcome Uncertain: Precision Temperature Markets Reward Patience, Not Conviction

The 26% price for a 25°C Seoul high on May 19 is reasonable given the distribution of possible outcomes, but the thin liquidity means this number is one forecast update away from repricing. The market is pricing the uncertainty of a single meteorological measurement, not a trend.

What the market says: 26% probability for a 25°C high, with the remaining 74% distributed across more than ten alternative temperature bands. With resolution at 2026-05-19 12:00:00 less than 30 hours away, any significant forecast revision will hit a low-liquidity order book and move the price quickly.

Key unknown: The Korea Meteorological Administration’s final 24-hour surface forecast for Seoul on May 19 is the single data point that matters. If the predicted high shifts from 25°C toward 24°C or 26°C, the YES probability on this contract will reprice materially before the window closes.

Frequently Asked Questions

• What does 26% probability mean here? The market prices a 26% chance that Seoul’s official high on May 19 lands exactly at 25°C. The remaining 74% is split across more than ten other temperature bands, each with its own contract.
• What pays out on the NO side? Any official Seoul high reading other than 25°C resolves this contract NO. A reading of 24°C, 26°C, or any other temperature outside the 25°C band pays out the NO position.
• What data release would move this price? The Korea Meteorological Administration’s short-range forecast update for Seoul on the morning of May 19 is the most direct catalyst. A forecast change of one degree in either direction would reprice the contract significantly.
• When does this contract resolve? Resolution is set for 2026-05-19 12:00:00. The Korea Meteorological Administration’s official daily high temperature for Seoul on May 19 determines the outcome.
• Is the $21,371 volume reliable for pricing? At this volume level, the market is thin. Liquidity of $59,564 is real but narrow, meaning a small number of large bets could shift the price by several percentage points. Treat the 26% figure as indicative, not precise.

This analysis reflects market conditions as of 2026-05-18 06:34:21. Prediction market probabilities are volatile and shift as new data and regulatory decisions emerge, especially as the 2026-05-19 12:00:00 resolution date approaches. Lines.com does not accept bets or provide financial or gambling advice. All market outcomes are uncertain.