Highest temperature in Shanghai on August 21?

Platform comparison

Market context

Shanghai's highest temperature on 21 August 2026 will be recorded at Pudong International Airport Station and resolved via Weather Underground's Daily Observations table. The market currently reflects 0% implied probability, suggesting traders expect the settlement window to close without a qualifying temperature reading or are pricing in extreme uncertainty around the specific measurement methodology.

Historical August temperatures in Shanghai cluster between 32–36°C, with occasional peaks above 37°C during heat waves. The 2013 summer saw Shanghai reach 38.3°C; more recently, August 2022 peaked at 36.2°C. These precedents establish that mid-to-high 30s Celsius readings are routine for late summer in the region, making any outcome within that band statistically plausible. The 0% crowd probability likely reflects either low trader participation in this specific contract or confusion around the resolution source hierarchy—the explicit preference for Daily Observations over Day High & Low summaries introduces a technical dependency that may deter casual participation.

Traders should monitor China Meteorological Administration forecasts and any tropical cyclone activity tracking toward the Yangtze River Delta in late August 2026, as such systems can suppress or elevate temperatures materially. Funding rates on crypto derivatives markets remain secondary here; the contract's value derives entirely from Shanghai's actual atmospheric conditions on that date. Weather Underground's data feed reliability and any station maintenance windows during the settlement period warrant attention, as gaps in observation could affect resolution clarity.

Methodology

Methodologically this overview focuses on on-chain pricing: Polymarket's live mid comes from the Polygon conditional-token order book and settles automatically in USDC. The other three venues — Kalshi, Betfair, Manifold — sit alongside as off-chain reference points so you can see how the contract translates across regulatory and settlement regimes.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

UK Frequently Asked Questions

What are crypto prediction markets?

Crypto prediction markets are on-chain smart contracts where you buy YES or NO shares on a future crypto event (e.g. "BTC above $100k by year-end"). The market price between 0¢ and 100¢ is the implied probability.

What does a transaction cost on Polygon?

Polygon gas is typically under $0.01 per transaction. A full trade cycle (Approve + Order + Fill) totals around $0.03 — compared to $5-50 on Ethereum mainnet.

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%.