Lowest temperature in Hong Kong on August 8?

Platform comparison

Market context

Hong Kong’s overnight minimum on 8 August will be set by the Hong Kong Observatory’s final “Absolute Daily Min (deg. C)” reading, not by crowd sentiment or an intraday forecast. The exchange payoff is therefore binary around the published one-decimal Celsius value, with USDC settlement only after the Daily Extract is finalised and the market can no longer resolve until that data appears.

The current 0% YES price is far below the climate norm for early August, when Hong Kong is usually hot and humid. The Observatory’s own 9-day outlook for 8 August called for a temperature range of 28–35°C, with “extremely hot” conditions and isolated showers or thunderstorms later, while other August climatology sources put typical lows around the high-20s Celsius and note August is generally the hottest, wettest part of the year.[4][7][14] That framing matters because a low temperature outcome in the market’s target range would require an unusually cool reading relative to seasonal averages, rather than merely a mild day.

For traders, the key catalysts are the Hong Kong Observatory’s updates through the day, especially whether showers or thunderstorms arrive early enough to suppress the overnight floor, and the timing of the final Daily Extract publication that locks settlement. In crypto terms, the contract is effectively a short-dated weather basis trade against USDC, so wider BTC and ETH volatility is only relevant if it is feeding into venue liquidity, funding conditions, or whale risk appetite rather than the meteorology itself. Morning spot moves and derivatives positioning can affect order-book depth, but the resolution still turns on the Observatory’s published minimum, not market-implied weather odds.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically this overview focuses on on-chain pricing: Polymarket's live mid comes from the Polygon conditional-token order book and settles automatically in USDC. The other three venues — Kalshi, Betfair, Manifold — sit alongside as off-chain reference points so you can see how the contract translates across regulatory and settlement regimes.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

UK Frequently Asked Questions

What are crypto prediction markets?

Crypto prediction markets are on-chain smart contracts where you buy YES or NO shares on a future crypto event (e.g. "BTC above $100k by year-end"). The market price between 0¢ and 100¢ is the implied probability.

Why USDC and not ETH or USDT?

USDC is the Polygon standard — audited reserves (Circle, monthly attestation), deepest order book, low gas costs. ETH volatility would distort probability quotes; USDT has thinner Polygon liquidity than USDC.

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%.