Highest temperature in Seoul (Incheon) on August 12?

Platform comparison

Market context

The market is pricing the likelihood of Seoul's highest temperature on 12 August 2026 falling within a specific range, with settlement determined by the Daily Observations table at Incheon International Airport rather than summary figures. The 0% implied probability suggests the crowd has effectively ruled out whichever temperature bracket this market represents—likely an extreme upper or lower bound given Seoul's typical August conditions.

Seoul experiences peak summer heat in August, with historical daily highs clustering between 28–32°C at Incheon. The 30-year August average sits around 29°C, though readings above 33°C occur roughly once per decade during heat waves. The 2018 heat wave pushed temperatures to 39.6°C in Seoul proper, whilst Incheon typically records 2–3°C cooler readings due to coastal influence. If this market represents a sub-25°C or above-36°C range, the 0% probability reflects genuine rarity rather than mispricing; conversely, if it covers the 28–31°C band where most August days cluster, the consensus may be underweighting normal variance.

Traders should monitor late-July 2026 weather patterns and any emerging forecasts from the Korea Meteorological Administration, which typically issues 10-day outlooks by early August. El Niño or La Niña conditions developing through 2025–2026 could shift seasonal temperature distributions, though their influence on individual August days remains modest. The resolution dependency on Wunderground's Daily Observations table rather than official KMA data introduces a minor technical risk; historical discrepancies between sources are rare but worth tracking if the market approaches settlement.

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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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 Who Will Win. 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%.