Highest temperature in Hong Kong on July 20?

Platform comparison

Market context

On 20 July 2026, the Hong Kong Observatory will record the highest air temperature in degrees Celsius across the city, a single real-world data point that determines whether this prediction market resolves as YES or NO. In prediction markets, a YES share pays out if the event occurs as defined, while a NO share pays out if it does not; here, the market asks whether the temperature falls within a specific range, with the current crowd-implied probability of YES sitting at 0%, suggesting traders believe the range is implausible.

Historically, Hong Kong’s July highs typically reach between 31°C and 34°C, with the absolute daily maximum rarely exceeding 36°C even during intense heatwaves. The 0% YES probability likely reflects a mismatch between the market’s defined range and these established climatic norms, as past records from the Observatory show no July 20 reading outside this band in the last two decades, making extreme outliers statistically negligible for settlement purposes.

Traders should monitor the Observatory’s Daily Extract publication schedule, which finalises the “Absolute Daily Max (deg. C)” only after data verification, usually within 24–48 hours of the date. No external announcements or weather forecasts will alter the outcome once the official figure is published, as settlement depends solely on this verified source. The Hong Kong Observatory’s climate data portal confirms that finalised daily extracts are the exclusive resolution source, meaning no pre-emptive news or model updates can override the recorded temperature once published.

Methodology

We track Highest temperature in Hong Kong on July 20? 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

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

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 Prediction Market UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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