Highest temperature in Seoul (Incheon) on August 17?

Platform comparison

Market context

Seoul's summer heat patterns are well-documented: August typically sees daily highs between 28–32°C, with occasional peaks above 33°C during heat waves. The Incheon International Airport weather station, which serves as the official resolution source, records observations at regular intervals throughout the day. For 17 August 2026, traders need to distinguish between the raw observation data (which Weather Underground logs in its Daily Observations table) and the simplified Day High & Low summary—the market explicitly prioritises the former, meaning programmatic data extraction should target the detailed observation records rather than relying on headline figures.

Historical August temperatures at Incheon show that readings exceeding 35°C occur roughly once every two to three years during particularly intense heat events, whilst temperatures above 37°C remain rare. The 0% crowd probability suggests either extreme confidence that August 17 will fall below the lowest temperature bracket offered, or insufficient liquidity and trader engagement on this specific date. Comparable markets on daily temperature extremes typically see probability shifts only when seasonal forecasts update or when real-time weather models begin converging on specific scenarios 7–10 days prior to the settlement date.

Traders monitoring this market should track the Korea Meteorological Administration's extended forecasts from mid-August onwards, as these typically incorporate atmospheric patterns 10–14 days ahead. Heat wave declarations, which South Korea's authorities issue when temperatures are forecast to exceed 33°C for three consecutive days, would serve as a leading indicator. API-based monitoring of Wunderground's historical station data and conditional order logic tied to forecast thresholds would allow systematic position management as the settlement window approaches.

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.

UK Frequently Asked Questions

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 Polymarket Review 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.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.