Highest temperature in Shanghai on August 8?

Platform comparison

Market context

Polymarket currently prices this Shanghai heat contract at **0% YES**, even though late-summer conditions in the city are normally warm enough to keep a high-temperature outcome very much in play. The market settles on the **highest temperature recorded in Weather Underground’s Daily Observations table** for Shanghai Pudong International Airport Station on 8 August 2026, so the relevant question is not the day’s average, but the single top reading that appears before the settlement window closes at 12:00 UTC. In on-chain terms, traders are holding conditional tokens on Polygon and settling in USDC, so the price reflects the market’s collective view of the exact Celsius range that will contain that peak observation.

For context, Shanghai’s August climate is typically hot and humid, with average highs around the low 30s Celsius and historical August records reaching about 40°C in city-level summaries. Comparable Weather Underground history for Shanghai has shown mid-to-high 30s Celsius highs around early August, including recent daily highs in the mid-30s Fahrenheit-converted range that correspond to roughly 35°C, which is consistent with the season’s usual heat profile. That means a 0% implied probability is less a statement that heat is impossible than a sign that the current contract is deeply mispriced relative to climatology and the broad range of plausible daily highs.

What matters most for traders now is the live Weather Underground feed for ZSSS, because the contract resolves from the Daily Observations table rather than the Day High & Low summary if the two differ. The main catalysts are simple: whether morning cloud cover, rain bands, or a passing typhoon suppresses the day’s peak, and whether the station posts a late-afternoon maximum after the settlement cut-off. Recent Shanghai weather coverage has repeatedly flagged August as a period of heat, humidity, and intermittent rain, so the key watchpoint is the intraday observation sequence rather than any single forecast headline.

Sources: 1 · 2 · 3 · 4 · 5

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

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

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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.

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%.