Highest temperature in Hong Kong on July 21?

Platform comparison

Market context

Hong Kong faces its peak summer heat on 21 July 2026, with the Hong Kong Observatory set to record the day’s absolute maximum temperature in degrees Celsius. The prediction market currently shows a 0% implied probability for the YES outcome, suggesting traders believe the temperature will fall outside the specific range offered, likely due to expectations of normal or slightly above-normal conditions rather than extreme outliers.

Historical data from recent July summers in Hong Kong shows maximum temperatures typically ranging between 31°C and 34°C, with extreme heatwaves occasionally pushing readings to 35°C or higher. The seasonal forecast for July–September 2026 indicates temperatures are expected to be normal to above-normal, influenced by the current ENSO status and climate model projections [1]. This aligns with the crowd’s low confidence in an extreme high, as above-normal does not necessarily imply record-breaking heat.

Traders should monitor the Observatory’s daily extract for the “Absolute Daily Max” once finalized, as settlement depends entirely on this published figure. No immediate weather announcements are expected before the date, but ongoing ENSO monitoring and regional climate updates could shift expectations if extreme heat signals emerge. The lack of divergence between sportsbook lines and prediction-market odds suggests consensus on a standard summer day rather than a heat anomaly.

Sources: 1

Methodology

We track Highest temperature in Hong Kong on July 21? 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.

FAQ

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 PolyGram. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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 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.