Highest temperature in Busan on August 18?

Platform comparison

Market context

Busan's August heat remains on track for typical late-summer conditions, with the Korea Meteorological Administration forecasting temperatures in the 32–34°C range for mid-August 2026. The 0% crowd probability suggests traders are pricing in either extreme uncertainty about the exact settlement threshold or a misalignment between expected temperatures and the market's resolution bands. August typically represents Busan's hottest month, with historical daily highs frequently exceeding 30°C during this period, though the city's coastal location moderates extremes compared to inland Korean regions.

Historical August data from Gimhae International Airport—the designated resolution station—shows daily maxima clustering between 29–33°C over the past decade, with occasional readings reaching 34–35°C during heat waves. The 2018 Korean heat wave pushed Busan to 34.6°C on 4 August, whilst more typical mid-August readings settle around 31–32°C. This historical range provides the baseline against which the current 0% probability should be evaluated; if the market's highest temperature band sits above 34°C, the low probability reflects genuine rarity rather than forecasting error.

Traders should monitor the Korea Meteorological Administration's extended outlook releases, typically issued fortnightly, for any revision to August's temperature trajectory. Tropical systems tracking towards the Korean peninsula in late July could suppress August heat, whilst a stable high-pressure system would elevate daily maxima. The Weather Underground Daily Observations table—specified as the resolution source—occasionally records differently from summary displays, so verification of the exact recording methodology at Gimhae will matter for settlement accuracy.

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

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

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%.