Highest temperature in Hong Kong on July 2?

Platform comparison

Market context

The real-world event hinges on the Hong Kong Observatory’s recorded absolute daily maximum temperature in degrees Celsius for 2 July 2026, measured to one decimal place. Historical data confirms July is typically Hong Kong’s hottest month, with average highs between 28°C and 32°C, while the Observatory’s seasonal forecast for July–September 2026 projects temperatures to be normal to above-normal [2][3]. This context makes the current crowd-implied probability of 0% for any outcome highly anomalous; the Polymarket frontrunner is actually 32°C at 45%, followed by 33°C at 28%, suggesting the 0% figure likely reflects a data display error or unresolved market state rather than genuine market consensus [1].

Traders approaching this programmatically must monitor the Observatory’s “Daily Extract” publication schedule, as the market cannot resolve until the official “Absolute Daily Max (deg. C)” is finalized [3]. Key catalysts include the latest ENSO status updates and climate model forecasts, which the HKO cites as drivers for the above-normal temperature projection [3]. Recent short-term forecasts indicate temperatures ranging from 25°C to 29°C through 9 July 2026, though this does not preclude a spike to 32°C or higher on the specific settlement date [5]. A power-user would script a bot to poll the HKO climate data endpoint directly for the finalised value once the Daily Extract is released, ensuring execution before the 2026-07-02T12:00:00Z settlement window closes.

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

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 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.