Highest temperature in Shanghai on August 20?

Platform comparison

Market context

Shanghai's weather on 20 August 2026 will determine which temperature band wins this contract. The market currently prices all YES outcomes at 0%, meaning traders are pricing near-zero probability that the highest temperature recorded at Pudong International Airport will fall into whichever range this particular contract covers. This pricing reflects either extreme confidence in a specific temperature range or illiquidity across the full set of conditional tokens spanning the possible outcomes.

August in Shanghai typically sees daily highs between 32–35°C, with occasional peaks above 36°C during heat waves. Historical data from Weather Underground shows that temperatures exceeding 37°C occur roughly once every three to five years in mid-August, whilst readings below 30°C are exceptionally rare. The 0% probability currently assigned suggests the crowd has concentrated conviction elsewhere in the range distribution, or that this particular bracket sits outside the modal expectation for late summer conditions at the airport station.

Traders monitoring this contract should track China Meteorological Administration forecasts released in early August 2026, which typically provide reliable 10–14 day outlooks for major cities. The resolution hinges on Weather Underground's Daily Observations table from Pudong station specifically—not summary figures—so any discrepancies between reporting sources will be settled against that primary feed. Typhoon activity in the Western Pacific during mid-August could materially shift temperature outcomes, as tropical systems occasionally bring cooler, wetter conditions to the Yangtze River Delta region.

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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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

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%.