Highest temperature in Seoul (Incheon) on August 20?

Platform comparison

Market context

Seoul's weather on 20 August 2026 will be measured at Incheon International Airport, with the day's peak temperature determining which bracket resolves YES. The market currently prices all temperature ranges at 0% probability on Polygon, suggesting either a technical listing issue or extreme uncertainty about settlement mechanics. Traders are effectively pricing in either a data unavailability scenario or genuine confusion about how Weather Underground's Daily Observations table will record that specific date.

August temperatures at Incheon historically cluster between 26–32°C, with extremes occasionally reaching 34–35°C during heat waves. The past decade shows only three days exceeding 33°C in mid-August, making higher brackets statistically improbable but not implausible. The 0% crowd probability appears disconnected from baseline climatology; comparable August days at the same station typically settle into mid-to-upper 20s Celsius under normal conditions, suggesting traders may be waiting for explicit range definitions before committing USDC to conditional tokens.

The resolution hinges entirely on Weather Underground's Daily Observations table availability and accuracy for that date. South Korea's Korea Meteorological Administration publishes official forecasts and historical data independently, but this contract explicitly requires Wunderground's specific data source. Traders should monitor whether Wunderground maintains consistent station reporting through 2026 and whether any API changes or data migration could affect settlement. The settlement window closes at 12:00 UTC on 20 August, creating a tight window for data confirmation before conditional token redemption on Polygon.

Methodology

We track Highest temperature in Seoul (Incheon) on August 20? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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 Scam?. 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%.