Highest temperature in Hong Kong on July 1?

Platform comparison

Market context

The highest temperature recorded in Hong Kong on 1 July 2026 will determine the outcome of this prediction market, with the Hong Kong Observatory’s official “Absolute Daily Max” serving as the sole resolution source. Today, Polymarket prices the YES contract at 0%, implying the crowd believes the temperature will not fall within the specified range. This on-chain pricing, settled in USDC on the Polygon network via conditional tokens, reflects a stark divergence from historical July heat patterns, where temperatures routinely exceed 32°C.

Historical data frames this 0% probability as highly unusual. July in Hong Kong is consistently the height of summer, with average highs between 32°C and 33°C and frequent peaks reaching 34°C or higher. The Hong Kong Observatory’s seasonal forecast for July–September 2026 explicitly predicts normal to above-normal temperatures, reinforcing that extreme heat is the norm rather than an anomaly [1][7]. Even recent hourly readings at 1 a.m. on 1 July 2026 recorded 29°C, suggesting daytime highs will comfortably surpass 32°C [9].

Traders should monitor the Observatory’s upcoming “Daily Extract” publication, which finalises the official temperature data, and watch for any sudden shifts in the southwest monsoon that could suppress daytime heating. A strengthening monsoon pattern has already pushed overnight minimums to exactly 28°C in recent days, a trend that may influence daytime peaks [8]. The resolution cannot occur until the Observatory publishes the data, making the timing of this release the critical catalyst for market settlement.

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.

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 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 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.