Highest temperature in Hong Kong on July 5?

Platform comparison

Market context

The real-world event at hand is the peak daily temperature recorded by the Hong Kong Observatory on 5 July 2026, a date historically synonymous with Hong Kong’s most intense summer heat. With the crowd-implied probability of a “YES” resolution sitting at 0%, the market currently treats any temperature exceeding the highest historical range as an impossibility, effectively betting on the underdog outcome of a record-breaking day.

Historically, July is Hong Kong’s hottest month, with average highs around 31.8°C and peak recorded monthly maximums reaching 35.7°C since 1885[3][6]. In July 2025, temperatures rose to around 35°C across many locations, with the Observatory recording 34.3°C on 7 July[7]. This pattern suggests the consensus is firmly anchored in the 34–35°C band, leaving little room for contrarian value unless a rare tropical cyclone or extreme urban heatwave pushes temperatures beyond 36°C, a scenario the market currently dismisses.

Traders should monitor the Hong Kong Observatory’s daily weather bulletins and any incoming tropical cyclone warnings, as these can drastically alter temperature trajectories. Recent reports note that July 2026 forecasts predict daily highs between 31°C and 35°C, with overnight lows of 26–28°C[4]. The key dependency is the finalisation of the “Daily Extract” data, which will only be published after the settlement window closes. Until then, the 0% implied probability remains a reflection of historical inertia rather than a definitive forecast of the coming day’s weather.

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 Who Will Win. 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 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.

Do I need to KYC for this market?

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

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.