Highest temperature in Hong Kong on July 3?

Platform comparison

Market context

The underlying event is the official daily maximum temperature recorded by the Hong Kong Observatory on 3 July 2026, measured in degrees Celsius to one decimal place. This market currently shows a 0% implied probability for any outcome, suggesting the crowd sees no chance of the event occurring within the defined resolution ranges, despite July being Hong Kong’s hottest month.

Historically, Hong Kong’s July highs consistently exceed 31°C, with the seasonal forecast for July–September 2026 predicting normal to above-normal temperatures [2]. AccuWeather’s monthly data indicates daily highs typically range from 86°F to 96°F (30°C to 36°C) [3], and recent forecasts for 3 July 2026 already list a maximum of 31°C [4]. This divergence between the 0% market probability and the clear historical and forecasted heat frames the contract as potentially mispriced, especially when compared to sportsbook lines on similar weather events that often assign meaningful odds to high-temperature outcomes.

Traders should monitor the Hong Kong Observatory’s finalised “Daily Extract” for 3 July 2026, which will publish the official “Absolute Daily Max” once data is confirmed [6]. Key catalysts include real-time updates from the 9-day forecast [10] and any sudden shifts in ENSO status, which the seasonal forecast notes as a factor influencing temperature trends [2]. A recent forecast for the week ending 7 July 2026 also mentions mainly cloudy conditions with light rain, which could temporarily suppress peak temperatures [7], though this remains unlikely to override the broader seasonal trend of above-normal heat.

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.

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.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.