Highest temperature in Hong Kong on August 11?

Platform comparison

Market context

Hong Kong’s highest temperature on 11 August will be set by the Hong Kong Observatory’s official daily extract, so the contract is really a bet on the city’s midday heat rather than on the broader weather headline. For context, recent forecast pages pointed to a hot, humid day with highs around 34–35°C, which is consistent with the market’s contract-specific pricing but far above the 0% YES crowd-implied figure currently shown on the venue. [3][6][8]

That 0% reading looks disconnected from the underlying climate signal. Hong Kong has a strong late-summer heat profile, and the Observatory’s own historical records show that August can produce maxima well into the mid-30s Celsius; in 2025, the city’s observatory station reached 36.9°C, breaking the long-standing record. The comparison point for traders is therefore not “will it be hot?”, but whether the official station finishes in a narrow temperature bucket, usually shaped by cloud cover, showers and the timing of the daily peak. [5][9][7]

The main catalysts are the Observatory’s hourly readings through the afternoon and the final publication of the “Daily Extract”, since the market cannot settle until that data is posted. A recent hourly bulletin system is already in place for tracking intra-day heat, and forecast services have been highlighting showers early and mostly cloudy conditions, which can trim the extreme end of the range without removing the odds of a very warm maximum. Cross-platform, the useful contrast is clear: sportsbook-style weather lines have been clustering around a mid-30s Celsius outcome, while the current market price is effectively saying the opposite, implying either stale trading or an unusually aggressive view that the official max will miss the forecast band. [11][6][3][7]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Hong Kong on August 11? 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

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