Lowest temperature in Hong Kong on August 5?

Platform comparison

Market context

Polymarket is pricing the Hong Kong Observatory’s overnight low for 5 August at a near-certainty level, with **27°C** at **96%** and **26°C** at **5%** on the contract page. In practice, that means traders on Polygon are treating USDC-denominated conditional tokens as a view on one very specific published number: the Observatory’s final “Absolute Daily Min (deg. C)” for that date, once the daily extract is released and accepted for resolution.[1][4]

The 0% crowd-implied probability on any other outcome sits against a weather backdrop that is unusually stable for August in Hong Kong: hot, humid, and often only modestly cooler overnight. The exchange itself cites official forecasts and model guidance projecting a **27°C** minimum under summer monsoon conditions, with light winds, high humidity and isolated showers curbing nocturnal cooling.[1] That makes the market readable as a test of whether the city gets an ordinary tropical night rather than a meaningful radiational dip, and 2025 offers a useful comparator: the Observatory recorded a much lower **24.0°C** minimum on 5 August last year during heavy rain, showing how rainfall timing can shift the floor even in midsummer.[15]

The main catalyst is not a policy release but the timing and content of the Observatory’s daily publication cycle, because this market cannot resolve until the relevant daily extract is finalised.[1][4] Traders should watch the Hong Kong Observatory’s forecast updates, regional weather statements and any late-day shower or wind changes that could affect the overnight minimum, alongside the exchange’s rule that later revisions do not count for resolution.[1][6] With settlement ending at 12:00 UTC, the practical question is whether the official minimum lands exactly where the market expects, not whether daytime heat persists.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Lowest temperature in Hong Kong on August 5? 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%.