Highest temperature in Hong Kong on June 26?

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Market context

On 26 June 2026, Hong Kong will experience its peak daytime heat, with the Hong Kong Observatory recording the absolute daily maximum temperature in degrees Celsius. This real-world event determines the resolution of a prediction market where the crowd currently implies a 0% probability of the temperature falling into the highest expected range, a stance that diverges sharply from seasonal forecasts and recent heat records.

Historical data frames this probability as unusually cautious. Long-term averages suggest daytime maxima of 30°C in June, yet the Hong Kong Observatory’s seasonal forecast for June–August 2026 explicitly predicts above-normal temperatures due to current ENSO conditions [2]. Recent history reinforces this divergence: Hong Kong recently recorded its hottest day of the year so far at 34.6°C, triggering a hail warning [9], while the Observatory has shared an outlook bracing for a heatwave hitting 33°C [6]. These facts contradict the market’s implied certainty that extreme highs will not occur.

Traders must monitor the Observatory’s finalised “Daily Extract” for the specific date, as the market cannot resolve until this data is published. Key catalysts include the timing of the official release and any updates on tropical storm passages, which affect roughly 1.4 days in June [1]. The forecast also notes normal to below-normal rainfall, increasing the likelihood of sustained heat [2]. A recent report on the year’s hottest day confirms temperatures can soar past 34°C, suggesting the 0% probability may underestimate the risk of record-breaking heat [9].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Hong Kong on June 26? on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

On PolyGram, which mirrors the Polymarket order book at 0% fees. 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.

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 it cost to trade on PolyGram?

Zero. PolyGram routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, PolyGram triggers a quick verification flow that finishes in minutes.