Highest temperature in Shanghai on August 9?

Platform comparison

Market context

Polymarket has this Shanghai temperature contract priced at **0% YES**, so the market is currently treating an outcome in the target temperature band as extremely unlikely. The contract settles in USDC on Polygon through conditional tokens, and the real-world reference point is the *highest* temperature logged in Weather Underground’s **Daily Observations** table for Shanghai Pudong International Airport on 9 August, not the summary high shown elsewhere.

For context, Shanghai in August is usually very hot and humid, with long-run sources putting typical daytime highs around the low 30s °C and occasional peaks well into the mid-30s °C. Forecasts for 9 August 2026 are mixed but broadly point to rain and a cooler day than the seasonal norm: AccuWeather shows 85°F/29°C with a high chance of precipitation, while other forecast pages cluster around 28–33°C, and Weather25’s historical-style averages still imply that 31°C-plus is normal for early August. That means traders looking at the current 0% price are effectively saying the contract is misread only if the airport station prints an unusually warm observation despite the rain.

The main catalyst is the hour-by-hour evolution at Shanghai Pudong International Airport, because a brief warm spike before showers or a late-morning break in cloud can still set the day’s maximum. Traders should watch the Weather Underground station feed rather than the forecast headline, since the settlement source is the observation table and the market window closes at 12:00 UTC on 9 August. Polling data in the forecast pages also suggests the weather is unsettled, with strong rain signals and wind, which usually makes the exact timing of the day’s peak temperature more important than the daily average.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Shanghai on August 9? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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%.