Highest temperature in Guangzhou on July 21?

Platform comparison

Market context

The market seeks the highest temperature recorded at Guangzhou Baiyun International Airport on 21 July 2026, with settlement based on Wunderground historical data. The 0% implied probability suggests traders have assigned negligible odds to whichever temperature bracket this market is testing—likely an extreme threshold well above typical July conditions in the region.

Guangzhou experiences peak summer heat in July, with historical highs consistently between 33–35°C at the airport station. The city's subtropical climate produces reliable heat during this period, though extreme outliers above 37°C are uncommon but not unprecedented. Comparable July days from the past decade show the airport station rarely exceeds 36°C, with readings typically clustering in the 34–35°C range. The 0% probability implies the market is pricing an outcome significantly outside this established pattern—either an unusually cool day or an extreme heat spike that defies recent norms.

Traders should monitor seasonal weather patterns emerging in June 2026, particularly any signals of an anomalous atmospheric setup. Tropical cyclone activity in the South China Sea during early-to-mid July could introduce moisture and cloud cover that suppresses peak temperatures, whilst a high-pressure system stalled over southern China would favour elevated readings. The settlement window closes at noon UTC on 21 July, giving traders access to real-time observations throughout the morning hours in Guangzhou before final resolution against Wunderground's recorded data.

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.

FAQ

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.

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