Highest temperature in Shanghai on August 15?

Platform comparison

Market context

Shanghai will experience peak summer heat on 15 August 2026, with the highest temperature recorded at Pudong International Airport determining settlement. The market currently prices this outcome at 0% YES across all temperature bands, reflecting the settlement window's closure date coinciding with the event itself—traders cannot yet observe the actual reading. On Polygon, USDC-denominated conditional tokens partition the outcome space into discrete ranges; the crowd has allocated zero probability mass to any single band, suggesting either extreme uncertainty or insufficient liquidity to establish meaningful pricing before the window closes.

Historical August temperatures at Shanghai Pudong show consistent patterns: the station typically records daily highs between 32–35°C during mid-August, with occasional peaks reaching 36–37°C during heat waves. Data from the past five years indicates that 15 August falls within the hottest fortnight of summer, though not the absolute peak; late July and early August often see marginally higher readings. The 0% probability across all ranges is unusual given this seasonal baseline and likely reflects the market's structural constraint—settlement occurs on the same day as the event, leaving no time for price discovery before resolution.

Traders monitoring this contract should track China Meteorological Administration forecasts released in early August 2026, which typically provide ten-day outlooks with reasonable accuracy for Shanghai's urban heat island effects. Tropical cyclone activity in the Western Pacific during mid-August could suppress temperatures through cloud cover and precipitation, whilst high-pressure systems anchored over eastern China would drive readings toward the upper end of historical ranges. Weather Underground's Daily Observations table, specified as the binding resolution source, occasionally differs from airport summaries due to sensor calibration timing; traders should verify the platform's methodology before settlement.

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

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.

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%.