Highest temperature in Chengdu on August 9?

Platform comparison

Market context

Polymarket is currently pricing **0% YES** on the contract, so the market is effectively saying the listed Chengdu airport station temperature range will not be hit in the settlement window. On-chain, that means traders are holding or minting conditional tokens against a USDC-denominated outcome on Polygon, with the final print coming from Weather Underground’s **Daily Observations** table rather than the summary “Day High & Low” figure.

For context, Chengdu in August is usually hot, humid and rain-prone, with typical highs clustered in the low 30s Celsius and occasional spikes higher. Forecast sources in the scrape point to a high near **32–34°C** for 9 August, while climate guides note that August can still reach the high 30s on some days. That makes a zero price look less like a view on a cool day and more like a hard scepticism that the *specific* airport-observation band will be matched at the required timestamp and station.

The main things to watch are the live observations at Chengdu Shuangliu International Airport, not city-wide forecasts, because the market settles on the station record and a range bucket. Traders should also watch for timing issues around the settlement cut-off at **12:00 UTC**, since a noon UTC deadline maps into the local afternoon in Chengdu, when the day’s peak may already have printed. Forecast updates, thunderstorms, or a delayed warm-up matter here because the contract is sensitive to the single highest observed reading rather than the average daily temperature.

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.

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%.