Highest temperature in Seoul on July 17?

Platform comparison

Market context

Seoul faces its peak summer heat on 17 July 2026, with the Incheon International Airport station expected to record the day’s highest temperature in degrees Celsius. The Polymarket contract for this event currently prices the “YES” outcome at 0%, yet the underlying distribution heavily favours the 31°C range, which holds a 76% implied probability, while 32°C or higher sits at 22% [1]. This stark divergence between the binary “YES” price and the granular temperature odds suggests the market is treating the binary question as a specific threshold breach that has not been defined in the contract’s resolution logic, leaving traders to interpret the 31°C frontrunner as the de facto settlement point.

Historically, mid-July in Seoul sees average highs near 28–30°C, with extreme days occasionally pushing past 32°C during heatwaves driven by the North Pacific subtropical ridge. The current 76% weighting on 31°C aligns with recent comparable cases where Seoul recorded 30–31°C in July 2024 and 2025, indicating the market is pricing a typical but warm summer day rather than an outlier event [1]. The 0% “YES” probability likely reflects a structural mismatch in how the binary question is framed against the actual temperature range resolution, not a belief that no heat will occur.

Traders should monitor the Korea Meteorological Administration’s daily heatwave advisories and the real-time Wunderground feed for the Incheon station, which serves as the official resolution source. Any sudden shift in the 31°C probability above 80% or a jump in the 32°C+ share would signal a developing heatwave, potentially triggered by updated ridge forecasts or humidity spikes. A recent report from Yonhap News noted that Seoul’s July 2026 heat outlook remains “above average” due to persistent high-pressure systems, reinforcing the 31°C consensus [1]. On-chain mechanics on Polygon using USDC and conditional tokens allow precise entry into these temperature ranges, letting traders hedge or speculate without binary ambiguity.

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 Kalshi UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Kalshi UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.