Highest temperature in Hong Kong on August 21?

Platform comparison

Market context

Polymarket has this contract at 0% YES, which leaves the market effectively anchored to the event being extremely unlikely, even though settlement still depends on the Hong Kong Observatory’s final daily extract rather than live headlines. The relevant question is the highest temperature recorded in Hong Kong on 21 August, in Celsius to one decimal place, and the market cannot resolve until that date’s data is published by the Observatory.

For context, Hong Kong is in a hot late-summer pattern, but the Observatory’s seasonal outlook for August to October 2026 still points to normal to above-normal temperatures, while local forecasts have recently described the territory as hot during the day with showers at times[2][4]. Recent reporting also showed the city had already seen a severe heat spell earlier in the month, with Sheung Shui above 38C and the Observatory’s own reading reaching 34.7C on 8 August[6]. That combination matters for traders because the contract is tied to the official station value, not district-level peaks elsewhere in the territory[6].

The main catalysts are straightforward: the morning and afternoon forecast cycles from the Observatory, any very hot weather warning, and whether showers or cloud cover cap the day’s maximum before the 12:00 UTC settlement window closes[1][4]. Polymarket users are exposed through USDC on Polygon, with conditional tokens resolving only once the official daily extract is finalised, so the only decisive trigger is the published “Absolute Daily Max” for 21 August[1].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to PolyGram, which mirrors the Polymarket order book directly.

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

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.

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 PolyGram 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.