Lowest temperature in Hong Kong on August 9?

Platform comparison

Market context

The event is the lowest temperature the Hong Kong Observatory records for Hong Kong on 9 August, settled from the “Absolute Daily Min (deg. C)” in the final Daily Extract. Early forecasts point to a very warm night and an exceptionally hot day, with the Observatory’s 9-day forecast showing 29–36°C and the official weather notice saying “mainly fine” with “extremely hot” conditions during the day[2][9].

A 0% crowd-implied YES price is consistent with how markets often read a one-day weather contract before the relevant data is published: the payout depends on an exact observed minimum, not the forecast high. Comparable August climatology for Hong Kong is still broadly hot and humid, with average night temperatures in the mid-to-high 20s Celsius and rainfall common, but the current setup is tilted towards a warm minimum rather than an unusually cool one[13][18]. AccuWeather’s intraday view likewise shows an 84°F low for 9 August, reinforcing that the market is pricing a minimum well above any cool-band outcome that would be needed for a lower settlement bracket[7].

Traders should watch the Hong Kong Observatory’s updated forecasts, any overnight rain or thunderstorm development, and the timing of the final Daily Extract, because settlement cannot occur until the published Observatory data is finalised[2][17]. On-chain, the contract should continue to trade like a short-dated event line: liquidity and USDC availability matter more than direction once the market is close to expiry, while broader BTC/ETH moves only matter if they shift risk appetite and whale flow across prediction markets rather than altering the weather itself.

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 does a transaction cost on Polygon?

Polygon gas is typically under $0.01 per transaction. A full trade cycle (Approve + Order + Fill) totals around $0.03 — compared to $5-50 on Ethereum mainnet.

Can I use Bitcoin directly?

No, Polymarket operates exclusively in USDC on Polygon. You can bridge BTC to USDC via an exchange or bridge service and deposit on Polygon — typically 10-30 minutes processing time.

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%.