Highest temperature in Seoul (Incheon) on August 17?

Platform comparison

Market context

Seoul's weather on 17 August 2026 will depend on the intensity of the East Asian summer monsoon and any tropical systems tracking through the Korean peninsula during mid-August. The 0% implied probability suggests the market crowd expects either a specific temperature range to be ruled out entirely or uncertainty about which bracket will resolve. August temperatures in Seoul typically peak between 28–32°C, though heat waves can push daily highs above 35°C. The settlement mechanism using Incheon International Airport's Daily Observations table (rather than summary figures) introduces a technical specification that matters: airport stations often record slightly different maxima than city-centre sites due to exposure and measurement timing.

Historical August data from Incheon shows considerable variability. The station has recorded August highs ranging from 23°C in cooler years to 37°C during intense heat events. The 2018 heat wave pushed temperatures to 39°C in early August across the region, whilst wetter monsoon patterns in other years have capped peaks at 26–28°C. This 8–11°C spread across comparable historical dates illustrates why a single-day forecast carries genuine uncertainty, particularly when the market settles on a specific range rather than an exact figure.

Traders should monitor tropical cyclone forecasts from late July onwards, as any system tracking north towards Korea would suppress temperatures significantly. The Korea Meteorological Administration's extended outlook, typically issued in mid-July, will clarify whether August 2026 tracks towards a heat-dominated or monsoon-influenced pattern. Upper-atmosphere pressure patterns and sea-surface temperatures in the Western Pacific will be the primary drivers of whether Seoul experiences a typical summer day or an outlier event.

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.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

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%.