Highest temperature in Hong Kong on August 18?

Platform comparison

Market context

On 18 August 2026, the Hong Kong Observatory will record the day's highest temperature in degrees Celsius, measured to one decimal place. The market currently shows 0% implied probability across all temperature ranges, reflecting that traders have not yet committed capital to any outcome band. Settlement depends on the Observatory's published "Daily Extract" data, which typically becomes available within days of the measurement date. USDC conditional tokens on Polygon will resolve once the Observatory finalises its official reading.

Hong Kong's August temperatures cluster tightly around historical norms. The city's average daily maximum in August sits near 31–32°C, with extreme heat days occasionally pushing toward 34–35°C. The all-time August record high is 36.3°C, set in 1990. Over the past decade, August 18 specifically has seen highs ranging from 28.5°C to 33.8°C, with most years landing between 30°C and 33°C. This consistency means the bulk of trading activity typically concentrates in the 31–33°C bands once the market becomes active.

Traders should monitor the Hong Kong Observatory's seasonal forecasts and any tropical cyclone warnings issued in early August 2026, as these significantly alter temperature trajectories. The Observatory publishes monthly outlooks that flag anomalous conditions; any advisory suggesting above-normal heat or unusual weather patterns would shift probability weightings. Additionally, the timing of monsoon transitions and any upper-level atmospheric patterns affecting the region in mid-August will drive intraday price movements as the settlement date approaches.

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.

FAQ

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.

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.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.