Highest temperature in Hong Kong on July 17?

Platform comparison

Market context

The underlying event is the peak air temperature recorded by the Hong Kong Observatory on 17 July 2026, measured in degrees Celsius to one decimal place. This market resolves strictly against the official “Absolute Daily Max” figure published in the Observatory’s Daily Extract, meaning any unverified sensor reading or third-party forecast carries no weight for settlement.

Historically, mid-July in Hong Kong sees daily maximums typically ranging between 31°C and 34°C, with extreme outliers rarely exceeding 35°C. The current 0% YES probability implies the market expects the temperature to fall outside the specific range offered, likely because the implied range is either too narrow or misaligned with seasonal norms. Programmatic traders should back-test historical Daily Extract CSVs from the Hong Kong Open Data portal to calibrate range expectations, using the full-year maximum temperature dataset to identify volatility clusters around this date [1].

Key catalysts include the Observatory’s publication schedule for the Daily Extract, which usually finalises data within 24–48 hours after the event date. Traders must monitor the official weather.gov.hk API endpoint for the CLMMAXT dataset, as delays in data release can create temporary arbitrage windows before settlement. No external announcements or weather model updates alter the resolution source; only the finalized official record determines outcome. Recent operational updates to the Observatory’s data pipeline confirm consistent publication timing, reducing uncertainty around settlement latency [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

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

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 Review UK. 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.

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.