Lowest temperature in Hong Kong on August 8?

Platform comparison

Market context

Hong Kong Observatory’s final figure for 8 August will determine the market: the relevant event is the **lowest temperature** recorded that day, published later in the Observatory’s “Daily Extract” as the “Absolute Daily Min (deg. C)”. In plain terms, a **YES** share pays out if the final minimum falls inside the market’s specified temperature range, while a **NO** share pays out if it does not.

For context, Hong Kong is usually warm and humid in August rather than cool. The Observatory’s 1991–2020 normals put 8 August’s mean temperature at 29.0°C and mean minimum at 26.9°C, which is a useful anchor for how the day typically behaves.[1] Recent summers have also leaned hot: the Observatory described August 2024 as “an exceptionally hot August”, with mean daily minimum air temperature of 27.7°C, and August 2025 still ran above normal on minimum temperature despite very wet conditions.[14][9] That means the crowd-implied 0% YES should be read as the market saying this range is currently viewed as unlikely, not impossible.

What traders should watch is the weather pattern over the day and the publication timing of the official extract. Hong Kong can still see rain, cloud, or a cooler overnight minimum even in a hot month, so the key catalyst is whether conditions ease enough before dawn and how the Observatory records the final reading at its station. The resolution source is the Hong Kong Observatory itself, and the market cannot settle until the final data for 8 August is published on its climate pages.[1][7]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

UK Frequently Asked Questions

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Prediction Market UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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%.