Highest temperature in Seoul on July 20?

Platform comparison

Market context

Seoul faces its peak summer heat on 20 July 2026, with the market betting on whether the Incheon International Airport station will record a temperature within a specific range. The crowd currently assigns a 0% implied probability to the YES outcome, suggesting near-universal consensus that the temperature will fall outside the offered bracket. This extreme pricing implies the market views the event as virtually impossible, treating the favourite as the opposite outcome with overwhelming confidence.

Historically, July is Seoul’s wettest month, bringing a 43% daily chance of precipitation and averaging 11.2 mm of rain, which often suppresses peak temperatures through cloud cover and evaporative cooling [1]. Comparable cases from recent years show that while daytime highs frequently exceed 30°C, heavy rainfall events can cap temperatures significantly lower, creating a volatile distribution that rarely clusters in narrow, high-temperature bands. The 0% probability likely reflects a belief that either a cooling rain system will intervene or the heat will simply not reach the threshold required for the YES outcome.

Traders should monitor real-time weather models for the Incheon station, specifically watching for sudden shifts in precipitation forecasts or monsoon front movements that could alter the thermal profile. A key catalyst is the daily Wunderground update for RKSI, which will provide the definitive highest temperature once the settlement window closes at 12:00 UTC on 20 July. Any unexpected announcement of a heat dome or a sudden drop in humidity could create a contrarian angle, though current data suggests the underdog (the YES outcome) holds little value unless a major forecast reversal occurs.

Sources: 1

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Who Will Win 2026. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.