Highest temperature in Hong Kong on August 4?

Platform comparison

Market context

Hong Kong’s official peak temperature for 4 August will be set by the Hong Kong Observatory’s final “Absolute Daily Max (deg. C)” reading, measured in one decimal place and published later in the relevant Daily Extract.[8][15] In prediction-market terms, a **YES** share pays out if the final published value falls in that outcome’s temperature band; a **NO** share pays if it does not. Because settlement waits for the Observatory’s completed data, the market remains open to late changes until the official extract is posted.[8][15]

The 0% crowd-implied probability is best read as a sign of either very low interest or a market that has not yet fully repriced to the weather setup, rather than as a literal forecast of impossibility.[2] Hong Kong’s August climate is typically hot and humid, with guide data and forecast pages pointing to daily highs around 30-32°C and occasional readings above that range.[3][7][11] Recent reporting also shows the city has already seen temperatures in the mid-30s during 2026 heat episodes, which is useful context when judging whether the final reading lands in a lower or higher band.[5][6][10]

A trader should watch the Hong Kong Observatory’s short-range forecast, regional readings and any thunderstorm or typhoon signals, because cloud cover and heavy rain can suppress the day’s maximum even in a very warm month.[8] The key dependency is not a general city weather headline but the Observatory’s final daily extract for 4 August, which can differ from live daytime readings if the highest value is recorded at a later station update.[4][8][15] Market participants will also be reacting to whether afternoon convection develops over the territory, since a brief clear spell can lift the maximum quickly, while persistent rain can cap it near the low 30s.[1][16]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Hong Kong on August 4? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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

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 Prediction Market UK. 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.

Do I need to KYC for this market?

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