Highest temperature in Seoul (Incheon) on August 21?

Platform comparison

Market context

Seoul's weather on 21 August 2026 will be measured at Incheon International Airport Station, with the day's peak temperature determining which range this market settles into. The contract currently trades at 0% implied probability across all temperature bands, suggesting either extreme uncertainty amongst traders or a technical issue with how the market has been priced on Polygon. Resolution hinges on the Daily Observations table from Weather Underground rather than summary figures, a distinction that matters when intraday temperature spikes occur between official recording intervals.

August in Seoul typically peaks between 28–32°C, with the city experiencing its most intense heat during mid-to-late summer when Pacific high-pressure systems dominate East Asia. Historical data from Incheon shows that temperatures exceeding 33°C occur in roughly one-third of August days, though extreme heat above 35°C remains less common. The 2018 heat wave pushed Seoul to 39.6°C, establishing the upper bound for what's meteorologically possible during this period. Current crowd pricing at zero across all bands is anomalous given these seasonal baselines and suggests traders may be awaiting clearer long-range forecasts before committing USDC to conditional token positions.

Traders should monitor the Korea Meteorological Administration's extended outlook, typically issued 10–14 days before the target date, which will signal whether Pacific typhoon activity or continental high pressure dominates late August 2026. Sea surface temperatures in the Yellow Sea and any tropical cyclone formation in the Western Pacific will be critical dependencies. The settlement window closes at 12:00 UTC on 21 August, leaving a narrow window for final price discovery once the day's actual conditions become apparent.

Methodology

This page reviews Highest temperature in Seoul (Incheon) on August 21? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Polymarket Alternative UK, which mirrors the Polymarket order book at 0% fees.

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

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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%.