Highest temperature in Seoul (Incheon) on August 7?

Platform comparison

Market context

The measured high at Incheon International Airport on 7 August will be the settlement trigger, so the market is really pricing the day’s local maximum rather than Seoul city-centre conditions. Short-term forecasts for the capital point to a very hot spell, with Seoul expected to reach about 39°C today in one national broadcast forecast, while other current forecast sets show highs closer to the low- to mid-30s Celsius with rain or cloud around the edges of the day.[2][3][4]

That split matters because airport readings can sit several degrees below the urban core, and this contract settles on the highest observation at the airport station, not the felt heat elsewhere. Seasonal context also argues against treating a zero-priced YES as impossible: August in Seoul normally brings average highs around the mid-20s Celsius to low-30s Fahrenheit-equivalent, but forecast services and climatology both show that early August can still produce spikes into the high 30s Celsius during heatwave episodes.[1][14][17][18]

For traders, the main catalysts are the day’s actual hourly evolution, any late-morning convective rain, and the persistence or easing of the current heatwave warnings across the greater Seoul area.[2] If the hot air mass holds through the airport’s afternoon peak, the settlement range can move quickly; if showers, sea-breeze effects, or cloud arrive earlier than expected, the ceiling drops. In on-chain terms, this is a straight USDC binary on a single public weather print, so there is no basis risk from BTC or ETH unless broader crypto volatility alters liquidity, funding, or positioning into expiry.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reads Highest temperature in Seoul (Incheon) on August 7? on-chain. Polymarket's quote comes directly from the Polygon order book — the only comparable venue with on-chain settlement. Kalshi (USD, off-chain), Betfair (GBP/EUR, off-chain) and Manifold (play-money) are listed alongside for venue context. Every CTA routes to BTC Prediction, which mirrors the Polymarket order book directly.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

UK Frequently Asked Questions

What are crypto prediction markets?

Crypto prediction markets are on-chain smart contracts where you buy YES or NO shares on a future crypto event (e.g. "BTC above $100k by year-end"). The market price between 0¢ and 100¢ is the implied probability.

Why USDC and not ETH or USDT?

USDC is the Polygon standard — audited reserves (Circle, monthly attestation), deepest order book, low gas costs. ETH volatility would distort probability quotes; USDT has thinner Polygon liquidity than USDC.

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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.

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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%.