Highest temperature in Hong Kong on August 15?

Platform comparison

Market context

Polymarket has this contract at 0% YES, which leaves the market pricing a sub-12:00Z Hong Kong maximum that lands outside the specified range, even though the outcome still depends on the Hong Kong Observatory’s final “Absolute Daily Max” for 15 August. The event itself is straightforward: a single Celsius reading from the Observatory’s daily extract will settle the conditional tokens on Polygon, with USDC at risk until the official data is published.

For context, Hong Kong in August usually sits in the low 30s Celsius by day, with humid, storm-prone conditions often capping extreme heat but not ruling it out. The Observatory’s own climate notes describe afternoon temperatures that often exceed 31°C, while August 2025 finished with a month-high of 34.4°C at the Observatory, showing that mid-30s readings are entirely plausible in this season. That makes a zero-priced contract look like a strong view that the day’s peak will fail to reach a listed strike band, rather than a call on whether it will be cool in absolute terms.

The main catalysts are the Observatory’s daytime observations, any thunderstorm or rain warnings, and the timing of the finalized Daily Extract, because the market cannot resolve until that publication appears. Traders should also watch whether the morning/early-afternoon profile stays cloudy or whether a dry window opens enough for the official maximum to push higher before the settlement window closes at 12:00Z.

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Methodology

We track Highest temperature in Hong Kong on August 15? 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.

UK Frequently Asked Questions

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.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.