Highest temperature in Hong Kong on July 31?

Platform comparison

Market context

Hong Kong’s maximum temperature for 31 July will be set by the Hong Kong Observatory’s final daily extract, with the market resolving on the day’s **absolute daily maximum** in Celsius. At a crowd-implied **0% YES**, the favourite is clearly the *sub-32°C* side of the range, because late-July Hong Kong usually sits in the high-20s to low-30s rather than producing extreme spikes every day.[3][4][17]

That said, the historical frame is not dead. The Observatory’s July rankings show that the city can and does post very hot readings in midsummer, and recent reporting has described July as Hong Kong’s hottest month on record in one year, underlining that heat can persist for long stretches.[1][3] The consensus angle is therefore that the market is pricing in an ordinary-to-warm day, while the value spot, if any, sits with a contrarian lean towards the upper temperature bands if cloud cover breaks and the urban heat effect bites.

The trader’s catalyst is the official Hong Kong Observatory daily extract, which can only settle once the 31 July data is published and finalised, so intraday volatility matters less than the eventual station reading. Short-range forecasts and hourly readings from the Observatory are the practical watchpoints, alongside any weather-system shifts that could cap the maximum through rain, convection or seabreeze timing.[7][12][13] AccuWeather’s late-July outlook for Hong Kong also points to temperatures in the high-20s and around 30°C, which supports the underdog case for the higher brackets if the day runs hotter than the base forecast.[2]

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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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.

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.

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.