Highest temperature in Chengdu on August 9?

Platform comparison

Market context

Polymarket is pricing this Chengdu heat contract at **0% YES** today, so the current market is effectively saying the listed temperature bands are not being assigned any probability despite the event still being open on Polygon with USDC and conditional tokens. The real-world trigger is simple: the highest observed temperature at Chengdu Shuangliu International Airport on 9 August 2026, as resolved from Weather Underground’s **Daily Observations** table rather than the summary high/low box.

That 0% read sits against a climate that is usually warm to hot in August, but not extreme by inland China standards. Forecast providers cluster around the low-30s Celsius for today and the surrounding period, with current Chengdu forecasts showing highs around 32–34°C and August norms around 31–33°C, while historical guides describe August as humid, rainy and frequently in the mid-20s to low-30s Celsius.[1][3][4][10][11][17] Comparable cases therefore suggest the market is not pricing an exceptional spike above the usual range; rather, it is discounting the chance that the airport station prints a top-end reading that lands in the higher bands used by the contract.

For traders, the main catalysts are the intraday observation path at the airport station and any short-lived heating or convective rain breaks before the settlement window closes at 12:00 UTC. Chengdu forecasts today include thunderstorm/rain signals and modest wind, which can cap daytime maxima or create brief temperature spikes depending on cloud cover and shower timing.[2][8][15] The practical check is the Weather Underground observations feed itself, because the market settles on that table’s highest recorded Celsius reading, not the headline forecast or summary high.[19]

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

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Alternative UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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%.