Lowest temperature in Hong Kong on July 31?

Platform comparison

Market context

Hong Kong’s overnight minimum on 31 July is the key datapoint here, and the market will settle on the Hong Kong Observatory’s final “Absolute Daily Min” once the Daily Extract is published. For a programmatic workflow, that means the useful signal is not the afternoon peak but the confirmed station minimum, with the final print only usable after the Observatory posts the completed climate file.[10][7]

The 1% YES implies the market is pricing a very low chance of the lowest temperature landing in the YES range, which is consistent with Hong Kong’s late-July climate. The Observatory’s July normals put the city’s mean minimum around 25.0°C on 31 July, while broader historical summaries show July lows typically clustered in the high 20s to low 30s for daytime values and the mid-20s for minima, so a materially cooler print would usually need a strong overnight rain, cloud, or northerly change.[1][6][14] Past Observatory commentary also shows 31 July can still stay warm even after rain, with July 2023 seeing thunderstorms in the small hours before sunshine later in the day.[9]

For traders using bots, copy logic, or conditional orders, the main catalysts are the Observatory’s end-of-day publication timing and any late weather shift before the 12:00 UTC settlement window closes. The practical dependency chain is simple: watch the Hong Kong Observatory daily extract page, then compare the final one-decimal Celsius minimum against the market’s range map; until that file is finalised, the market cannot resolve.[10][2] If you are scripting alerts, the cleanest trigger is the Observatory update rather than generic forecast apps, because the settlement source is the official recorded minimum, not an estimate.[7]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Lowest temperature in Hong Kong on July 31? 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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

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.

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.

Do I need to KYC for this market?

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