Seoul June 21 Low Temp: Will It Hit Twenty Degrees?

Seoul’s overnight low on June 21 is sitting at a coin flip. The 20°C outcome carries a 52.5% implied probability right now, which means the market is barely leaning yes. Here’s what the measurements are telling us: a strong momentum surge pushed the 20°C contract up sharply in the last 24 hours, but the underlying meteorological signal is genuinely ambiguous. The market is pricing uncertainty, not science.

The market question is simple: will Seoul’s lowest temperature on June 21 land exactly at 20°C? The yes price sits at 0.53 and the no price at 0.48, with resolution set for June 21, 2026 at 12:00 UTC. Total volume has reached $10,599, with $7,951 of that trading in the last 24 hours alone.

How the Seoul Temperature Contract Resolves

This contract resolves YES if Seoul’s official lowest temperature on June 21 registers exactly 20°C. The resolution source is Polymarket’s designated weather data. The competing outcomes include 19°C, 21°C, 18°C, and a range from 15°C or below up to 25°C or higher, each trading as separate contracts.

• YES (20°C exactly): 0.53 per share, implying 52.5% probability that Seoul’s minimum hits this precise reading.
• NO (any other temperature): 0.48 per share, covering the entire field of competing outcomes from sub-15°C to 25°C or above.

For NO to pay out, Seoul’s official minimum simply needs to register anything other than 20°C on June 21. Seoul’s late-June overnight lows typically cluster in the 18°C to 22°C band, which spreads the probability mass across several adjacent outcomes. Any meaningful shift in the regional pressure system toward a warmer or cooler reading pushes capital immediately toward rival contracts.

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Momentum and Market Signals

The combined momentum signal here is unusually strong for a short-window weather market. The 20°C contract gained 14.0% over 24 hours and then surged another 22.5% in the last hour, with a trend score of 77.05. That kind of acceleration on a one-day weather market usually reflects a new forecast model run narrowing its consensus toward a specific low-temperature reading, though no official meteorological update has been publicly flagged as the precise trigger.

Total volume of $10,599 is modest, and the 24h volume of $7,951 represents most of the market’s lifetime trading. Liquidity sits at $14,422, which is thin enough that a single large order can shift the price noticeably. The data doesn’t care about the politics, but thin liquidity means price can move sharply on any updated forecast before resolution tomorrow.

• 1h and 24h change combined: The 20°C contract surged roughly 36% in combined momentum over the last day, suggesting a recent forecast convergence toward that exact reading.
• Liquidity depth: At $14,422, the order book is shallow. A $1,000 bet moves this market meaningfully.
• Volume concentration: Nearly 75% of total volume traded in the last 24 hours, indicating a very recent catalyst drove most of the action.
• Competing outcomes: The 19°C and 21°C contracts absorb significant competing probability. Any forecast shift of one degree changes the winning contract entirely.
• Trader sentiment: The 52.5% YES versus 47.5% NO split is as close to neutral as a prediction market gets.

Lines Analysis: Seoul’s June Low and the One-Degree Problem

Seoul sits in a late-June transition period where overnight lows are genuinely hard to pin to a single degree. The Korean Meteorological Administration’s forecast data for this period typically shows a 2°C to 3°C range of uncertainty for overnight minimums. The recent momentum surge into the 20°C contract likely reflects a model consensus narrowing toward that value, which is the clearest signal available right now.

The competing outcome risk is real and specific. The 21°C contract and the 19°C contract each hold meaningful probability mass. Seoul’s urban heat island effect nudges lows slightly warmer than surrounding stations, which modestly favors the 20°C to 21°C band over cooler readings. But a cloud cover shift or a brief northerly flow overnight could easily drop the reading to 19°C. That one-degree ambiguity is where this market lives.

• Korean Meteorological Administration forecast update before June 21 midnight: any tightening toward 20°C or away from it reprices all competing contracts simultaneously.
• Regional pressure gradient: a strengthening low-pressure system could push overnight temperatures warmer, shifting probability toward 21°C or 22°C.
• Cloud cover forecast: heavy cloud retention raises overnight lows; clear skies allow radiative cooling toward 19°C or below.
• Humidity levels: Seoul’s late-June humidity typically keeps overnight lows elevated, slightly favoring the 20°C to 22°C range over cooler outcomes.
• Competing contract prices: monitor the 19°C and 21°C Polymarket contracts directly. If either surges, it signals forecast model divergence from the current 20°C consensus.

With $10,599 in total volume, this is a thin market. The momentum surge into 20°C is the strongest directional signal available, but a 52.5% probability on an exact single-degree outcome in a city where late-June lows span a 4°C to 6°C historical range means the market is far from settled. The data favors 20°C marginally, but adjacent outcomes remain live threats.

LINES VERDICT

MARGINAL LEAN YES, HIGH UNCERTAINTY

The recent momentum surge into the 20°C contract is the clearest available signal, but a 52.5% probability on an exact temperature reading with less than $11,000 in total volume means this market is genuinely unresolved.

What the market says: At 52.5%, the market is calling this roughly even. The sharp 24-hour surge adds directional conviction, but thin liquidity means this price is highly sensitive to any forecast update before the June 21 resolution deadline.

Key unknown: The Korean Meteorological Administration’s final forecast model run for June 21 overnight is the single data point that would move this contract decisively, either confirming the 20°C consensus or shifting capital immediately to the 19°C or 21°C contract.