Highest temperature in Hong Kong on August 17?

Platform comparison

Market context

On 17 August 2026, the Hong Kong Observatory will record the day's highest temperature in degrees Celsius. A YES share in this market pays out if the actual maximum falls within a specific temperature band; a NO share pays out if it falls outside that band. Traders are essentially betting on whether Hong Kong will experience heat within a defined threshold on that particular date. The settlement hinges entirely on the Observatory's official "Absolute Daily Max" figure, published in their Daily Extract once the day's readings are finalised.

Hong Kong's August temperatures are remarkably consistent year-on-year, with historical daily maxima typically clustering between 31–34°C. The 30-year average high for mid-August sits near 32.5°C, though extremes have ranged from 29.8°C to 35.5°C depending on monsoon patterns and tropical cyclone activity. The current 0% crowd probability suggests traders are pricing in either an unusually cool day or confidence that the specified temperature band is genuinely unlikely—a signal worth examining against seasonal norms and any forecast anomalies.

The key variable is the East Asian summer monsoon's intensity in mid-August 2026 and any tropical cyclone activity in the Western Pacific. The Hong Kong Observatory issues extended forecasts roughly two weeks ahead; traders should monitor their monthly outlooks and any tropical cyclone warnings issued in early August, as these directly influence daily temperature ranges. Humidity and cloud cover during the settlement window will also matter: overcast conditions from passing systems typically suppress daily highs by 2–3°C compared to clear days.

Methodology

We track Highest temperature in Hong Kong on August 17? 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

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.

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%.