Highest temperature in Shanghai on August 9?

Platform comparison

Market context

Shanghai’s temperature on 9 August will be judged against the **highest reading at Shanghai Pudong International Airport Station** in Weather Underground’s *Daily Observations* table, so the key variable is the peak hourly observation rather than the day-high headline. Current forecasts point to a wet, windy day: AccuWeather shows 85°F with heavy rain and 97% precipitation probability, Timeanddate has 88°F with thunderstorms, and World Weather Online gives 29°C with heavy rain.[2][3][6]

A **0% YES** price implies the crowd is effectively ruling out an observation in the market’s target temperature band, which is unusual for Shanghai in August because climatology still allows hot spikes. WeatherSpark says daily highs in August “rarely” exceed 96°F, while AccuWeather’s August outlook spans 84°F to 94°F and other seasonal guides cluster near 32°C to 33°C, so a result depends on whether rain suppresses the afternoon peak or whether a brief pre-storm surge prints a higher reading before the heaviest precipitation.[1][12][15][18]

Traders should watch the overnight and morning observation trend on Weather Underground, plus any last-minute forecast revisions tied to monsoon bands or thunderstorms, because the market settles on the exact highest Celsius value recorded by the station through the settlement window. With the contract resolving in USDC, the practical driver is not only the weather itself but how sharply the forecast path changes into Sunday’s local afternoon; if near-term models stay clustered around the mid-to-high 20s Celsius, the current zero bid can persist, but any hotter updated run would matter immediately for pricing.[13][2][3]

Sources: 1 · 2 · 3 · 4 · 5

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%.