Highest temperature in Hong Kong on July 3?

Platform comparison

Market context

The Hong Kong Observatory’s official daily maximum temperature on 3 July 2026 is the real-world event this contract tracks, measured to one decimal in degrees Celsius. Today, Polymarket prices the “Highest temperature in Hong Kong on July 3?” contract with a 0% implied probability for the YES outcome, suggesting the crowd believes the temperature will fall outside the specific range being bet on. This stark pricing contrasts with the market’s frontrunner outcome of 31°C, which holds 48% implied probability, while 30°C sits at 36% [2].

Historical July data and recent seasonal guidance frame why traders read the current 0% probability as a range-specific signal rather than a temperature denial. The Hong Kong Observatory forecasts normal-to-above-normal temperatures for July–September 2026 amid the long-term warming trend, with daily highs typically ranging from 28°C to 32°C in summer [3][6]. AccuWeather’s July 2026 forecast shows highs between 86°F and 96°F (roughly 30°C–35°C), aligning with the market’s 31°C frontrunner [4]. The 0% YES probability likely reflects a mismatch between the bet range and these established climatology bands, not an expectation of cold weather.

Traders should monitor the Hong Kong Observatory’s final “Daily Extract” publication for 3 July, as the contract cannot resolve until this data is finalized [2]. Key catalysts include the Observatory’s seasonal update confirmations and any sudden shifts in ENSO status, which influence regional temperature anomalies [3]. Recent weather outlooks for south China note temperatures up to 25°C on Sunday, but this appears inconsistent with July’s typical heat; the more reliable seasonal forecast points to sustained warmth [7]. Watch for the official 31°C maximum temperature announcement, which currently carries the highest market weight [5].

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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

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.

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.