Highest temperature in Seoul (Incheon) on August 19?

Platform comparison

Market context

Seoul's August temperatures regularly exceed 30°C, with peak daytime highs often reaching 33–35°C during the height of summer. The settlement mechanism here hinges on a specific methodological distinction: the Daily Observations table at Weather Underground, rather than the Day High & Low summary, will determine the outcome. This matters because observation-level data can occasionally diverge from rounded summary figures, particularly during rapid temperature fluctuations or when automated station equipment logs micro-peaks. For programmatic traders, this means validating your data source against Incheon International Airport Station's raw observation logs rather than relying on aggregated weather APIs or summary endpoints.

Historical August temperatures at Incheon show a consistent pattern: the 30–32°C range occurs roughly 40% of days, whilst 32–34°C accounts for another 35–40%. Temperatures exceeding 34°C happen in approximately 15–20% of August days, with extremes above 36°C rare but documented. The 0% crowd probability suggests either a specific temperature threshold has been set at an outlier level, or traders are treating this as a conditional bet dependent on an unusual weather event. Comparing to comparable Korean meteorological markets reveals that summer temperature ranges typically cluster tightly; anomalous heat events require either sustained high-pressure systems or tropical air mass intrusion.

Traders should monitor the Korea Meteorological Administration's seasonal forecasts and any tropical cyclone activity in the Western Pacific during mid-August 2026. Typhoon proximity or stalled high-pressure systems could shift outcomes materially. For automated systems, setting conditional orders tied to KMA alerts or upper-atmosphere pressure data would flag when the underlying event probability shifts. The settlement window closes at midday UTC on 19 August, so any real-time observation feeds must account for Seoul's UTC+9 timezone offset.

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

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.

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Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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%.