Highest temperature in Beijing on July 31?

Platform comparison

Market context

Beijing’s highest temperature on 31 July is typically a **hot-season** reading rather than an outlier, with July normals around 31–32°C and month-end daily highs often clustering in the low-30s. Historical day-specific data put 31 July’s average high at about 31°C, while the extreme high for that date is 37°C in one long-run climate table, so a contract resolving to a “yes” bucket above the low-30s would generally need a clear heat spike rather than a standard summer afternoon.[1][2][3]

That history helps explain why the current **0% YES** crowd-implied probability looks far away from the climatology but not necessarily from the settlement mechanics: the market is not asking whether Beijing will be hot, but whether the day’s peak at Beijing Capital International Airport lands inside the specific range tied to YES. Beijing has produced extreme summer heat well above 40°C in past years, including 41.9°C citywide record highs, yet those events are rare relative to the usual late-July pattern, which is why cross-platform pricing can stay muted even in a seasonally warm period.[3][4][15]

For traders, the main catalysts are the afternoon temperature trajectory at Beijing Capital International Airport and any short-lived convection, cloud cover, or rainfall that caps the day’s maximum before the local peak heating window. Because resolution uses Wunderground history for the airport station, the relevant comparison is the station’s final daily high rather than city-centre headlines or broader municipal averages, so sportsbook-style weather lines, prediction-market pricing, and any analyst view can diverge if they are built from different stations or forecast models.[5][13]

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

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

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 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.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.