Highest temperature in Seoul (Incheon) on August 18?

Platform comparison

Market context

Seoul's maximum temperature on 18 August 2026 will be measured at Incheon International Airport Station and resolved against the Daily Observations table on Weather Underground, with settlement occurring at midday UTC on that date. The market currently prices all temperature ranges at 0% probability, reflecting either incomplete order book depth or a technical settlement issue rather than genuine market consensus about the event itself.

August in Seoul typically sees peak summer heat, with historical highs clustering between 32–35°C at Incheon. The 2023 summer brought exceptional temperatures across South Korea, with Seoul recording 33.1°C on 18 August that year. Comparable August dates show consistent patterns: 18 August 2022 reached 31.2°C, whilst 2021 recorded 32.5°C. These precedents suggest the market should price mid-range outcomes (28–32°C) as most probable, given Seoul's reliable summer heat patterns and the absence of anomalous atmospheric conditions forecast for mid-August 2026.

Traders should monitor the Korea Meteorological Administration's seasonal outlooks released in July 2026, which typically forecast monsoon activity and heat dome positioning. Pacific typhoon tracking becomes material in mid-August; tropical systems can suppress temperatures or drive extreme humidity. The resolution mechanism's specificity—requiring Daily Observations data rather than summary highs—means traders should verify Wunderground's historical recording consistency at Incheon Station before committing capital. Any discrepancy between reported highs and the Daily Observations table has resolved previous weather markets unexpectedly.

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 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%.