Highest temperature in Chengdu on August 9?

Platform comparison

Market context

Polymarket is pricing this Chengdu heat contract at **0% YES** right now, even though the market settles off the **highest temperature in Weather Underground’s Daily Observations table** for Chengdu Shuangliu International Airport, not the summary high shown elsewhere. In practical terms, a buyer of YES on Polygon is holding a conditional token that only pays if the station’s recorded maximum on 9 August 2026 lands in the specified temperature range before the settlement window closes at 12:00 UTC. Chengdu’s early-August climatology sits in the low 30s Celsius, with long-run August averages around 30°C and historical records well above that, so a 0% price implies traders see the contract’s chosen range as either outside the likely daytime peak or effectively untradeable on current information.[1][10][13]

For context, Chengdu has a strong late-summer heat profile, with August often the city’s warmest month and daily highs commonly near 31°C, while extreme spikes can push much higher.[7][13][15] Comparable August 9 data also point to normal highs near 30–31°C rather than anything exceptional, and one August 9 history page shows a forecast high around 33.4°C for this date, with a long-run average high of 30.4°C.[1] On a contract like this, the key historical lesson is that the market is not about the forecast headline alone: it is about the exact station reading and the exact bucket used for resolution, which can diverge from consumer weather summaries.[4][10]

The main trader catalysts are the final few hourly updates from Weather Underground’s station page, any late-day rain or cloud cover that caps the peak, and the resolution timing versus the local diurnal maximum, which in Chengdu often comes in the afternoon rather than near the settlement cutoff.[4][19] Because the market resolves from the Daily Observations table, the most relevant dependency is whether the airport station posts a higher mid-afternoon reading before the window closes, not whether app forecasts or summary tiles show a different number.[4][10] Policy-wise, the on-chain outcome is binary and fixed once the oracle-relevant observation is in, so any discrepancy between nearby weather sites matters less than the exact Wunderground station print used for settlement.[4]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Chengdu 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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

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 PolyGram. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.