Highest temperature in Guangzhou on July 27?

Platform comparison

Market context

The market is pricing Guangzhou’s 27 July heat reading at **0% YES**, even though contracts settle on the highest temperature recorded at Guangzhou Baiyun International Airport Station and pay out in **USDC** through **Polygon** conditional tokens. With the trigger sourced from Wunderground’s daily history page, the practical question for Polymarket users is whether the station’s afternoon maximum lands inside the listed range rather than whether Guangzhou feels broadly hot or cool.

That zero price is best read against the local climate baseline rather than as a statement that a hot reading is impossible. A long-range Guangzhou forecast published on Weather Atlas shows daytime highs in the **33°C to 37°C** band over the surrounding period, which is consistent with midsummer conditions that often produce upper-30s readings at an airport station if cloud cover and rain hold off.[1] In that context, the market is effectively asking whether traders believe the day’s top reading will be materially below a typical late-July peak, and the 0% quote suggests the order book has placed almost no weight on that outcome.[1]

For a trader, the main catalysts are not policy or earnings releases but the weather mechanics that shift the station maximum: afternoon convection, thunderstorm timing, cloud build-up, and whether rainfall arrives before the day’s hottest window. Because the resolution source is a single airport station on Wunderground, small differences in local timing matter, and any change in the forecast for showers or lightning-active weather can move implied odds quickly.[1]

Sources: 1

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

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 Polymarket Scam?. 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.

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 Polymarket Scam? trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.