Seoul May 31 Low Temp: Will 17°C Hold?

Seoul’s overnight temperature forecast for May 31 is moving fast. The 17°C outcome has jumped more than 30 percentage points in 24 hours, and traders are now pricing it at 72.5% probability. That kind of momentum on a short-dated weather contract usually means one thing: a tightening forecast cone that traders are chasing in real time.

The market asks a simple question: what will Seoul’s lowest recorded temperature be on May 31, 2026? The 17°C outcome sits at $0.73 YES and $0.28 NO. The contract resolves at 12:00 UTC on May 31. Total volume stands at $9,410, with $6,871 of that traded in the last 24 hours.

How the 17°C Seoul Temperature Contract Works

This contract resolves YES if Seoul’s official lowest temperature on May 31 hits exactly 17°C. Resolution follows official meteorological measurement. The competing outcomes include 16°C, 15°C, 14°C, 13°C or below, 18°C, 19°C, 20°C, 21°C, 22°C, and 23°C or higher.

• YES ($0.73): Seoul’s May 31 overnight low lands at exactly 17°C per official measurement.
• NO ($0.28): The overnight low falls at any other temperature, from 13°C or below up to 23°C or higher.

The NO side covers a wide range. Seoul’s minimum temperature would need to settle at any value other than 17°C for the NO contracts to pay out. Late-season cold fronts or unseasonably warm nights pushing the low above 18°C or below 16°C would both collapse the YES price. Weather forecasts at this resolution carry meaningful error bands even 24 hours out.

Sponsored Partner

Momentum and Market Signals Pointing Hard at 17°C

The combined momentum signal here is striking. The 17°C outcome gained 27.5% in the last hour and 31.0% over 24 hours, with a trend score of 84.74. That pattern suggests traders are reacting to a specific forecast update, most likely a tightening weather model run placing Seoul’s May 31 overnight low squarely at 17°C.

Total volume of $9,410 is thin by prediction market standards. With more than 70% of that arriving in the last 24 hours, this market is illiquid enough that a single updated forecast or a shift in model consensus could reprice the 17°C outcome sharply in either direction before resolution. Liquidity sits at $58,793, which provides some cushion, but open interest is $0, meaning no significant capital is locked in waiting for resolution.

• The 1h and 24h momentum composite signals a coordinated move, not noise. The driver is almost certainly a forecast model update issued in the last 12 to 24 hours.
• Total volume of $9,410 is below $10M, placing confidence at MEDIUM. Thin order books mean price can gap on new data.
• Trader sentiment breaks 72.5% YES versus 27.5% NO, a strongly bullish lean toward the 17°C outcome.
• The 24h volume of $6,871 represents more than 70% of all volume ever traded in this contract. Participation accelerated sharply.
• No whale trades are present. Price movement reflects aggregated small-to-mid-size bets chasing the same forecast signal.

Lines Analysis: Seoul Overnight Low and the 17°C Thesis

Here’s what the measurements are telling us. Seoul’s late-May overnight lows typically cluster between 14°C and 19°C during the transition from spring to the early monsoon season. A 17°C minimum is well within the climatological range for May 31. If current numerical weather prediction models are converging on 17°C as the overnight minimum, the 72.5% probability reflects a genuine forecast signal, not pure speculation.

What makes the NO side real is the precision requirement. The contract resolves on exactly 17°C. Seoul’s observed overnight low could easily settle at 16.8°C or 17.3°C, both of which would round or report differently depending on the official measurement protocol. Korea Meteorological Administration data typically reports to the nearest 0.1°C or whole degree depending on the product. If resolution uses whole-degree rounding, the 17°C outcome gains further support. If it uses raw tenths, measurement precision becomes the risk. That ambiguity alone justifies the 27.5% NO price.

• Korea Meteorological Administration forecast updates in the next 12 hours will be the single most important price driver before resolution.
• Any shift in the 850 hPa temperature analysis over the Korean Peninsula would reprice competing outcomes like 16°C or 18°C.
• Resolution source methodology matters: whole-degree versus decimal reporting could swing the outcome entirely.
• A late cold front passage or stalled maritime air mass would push the low below 16°C and collapse the YES price.
• Conversely, sustained southwesterly flow keeping nighttime temperatures elevated above 18°C would benefit the 18°C and 19°C outcomes.

The data doesn’t care about the politics, and in this case there is no politics. There is only a 12-hour window, one measurement, and a forecast model that traders have decided to trust at 72.5%. The $9,410 total volume signals genuine conviction, but the thin order book means this price is fragile. One updated Korea Meteorological Administration bulletin shifting the overnight low forecast by a single degree would move this contract hard.

LINES VERDICT

LEANING YES, FRAGILE PRECISION

The momentum and trader positioning strongly favor the 17°C outcome, driven by what appears to be a converging weather model forecast. The market is pricing forecast confidence, not settled science, and the exact-degree resolution requirement keeps meaningful risk in the NO contracts.

What the market says: At 72.5% implied probability, the market has strong conviction that Seoul’s May 31 overnight low lands at 17°C. With resolution in under 24 hours, this price will move sharply on any Korea Meteorological Administration forecast update issued before midnight local time.

Key unknown: The single most important data point is the next Korea Meteorological Administration official forecast update for Seoul on May 31. Any shift in the projected overnight minimum by even one degree would reprice this contract dramatically given the exact-temperature resolution requirement.