Highest temperature in Seoul on July 10?

Platform comparison

Market context

The underlying event is the peak temperature recorded at Incheon International Airport on 10 July 2026, which will determine the settlement of this prediction market. Historical data from early July 2025 shows Seoul hitting 37.8°C, the highest reading for the 1–10 July period in 117 years of records [2][5]. Despite this extreme precedent, the current crowd-implied probability for 28°C sits at 0% YES, suggesting traders view a 28°C peak as statistically unlikely compared to the broader historical range of 22°C to 32°C for the first ten days of July [4]. A power-user evaluating this tooling would programmatically cross-reference Wunderground’s daily archives with the Korea Meteorological Administration’s official logs to identify if the 28°C threshold aligns with recent cooling trends or if it remains an outlier against the 37°C+ record heat [1][7].

Traders must monitor the immediate weather forecast for the Seoul metropolitan area, specifically looking for the onset of monsoon rains or cloud cover that could suppress daytime highs below 28°C. Recent reports confirm South Korea is grappling with a record heatwave, yet the settlement depends on the specific conditions at Incheon Airport rather than central Seoul [5]. A programmatically driven approach would involve setting conditional orders that trigger if the Wunderground hourly feed for Incheon drops below 28°C before 12:00 UTC on the settlement date, effectively hedging against the 64.5% implied probability that the high will not be 28°C [10]. The key dependency is the precise timing of the temperature peak, as the market resolves on the highest recorded value for all times on that day, requiring real-time data ingestion to validate the outcome against the 28°C strike [6].

Sources: 1 · 2 · 3 · 4 · 5

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 Fees. 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 Fees trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.