Highest temperature in Hong Kong on June 21?

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Market context

Hong Kong’s maximum temperature on 21 June will be set by the Hong Kong Observatory’s final **Absolute Daily Max (deg. C)** for that date, measured to one decimal place and only resolvable once the daily extract is published. For a trader building around the API or a rules engine, the key practical point is that intraday readings are not final settlement data; the market should be treated as pending until the Observatory posts the completed record.

The current **0% YES** implied probability is not a clean signal that the outcome is impossible; it is more likely to reflect thin positioning, a late-launch market, or the fact that settlement data has not yet been published. Nearby Polymarket temperature markets on adjacent dates have sat heavily concentrated in a single range, suggesting traders usually cluster around the most likely mid-30s band rather than spreading across many buckets[1][9]. Hong Kong’s June climatology also helps frame the range: the Observatory’s historical ranking shows monthly mean maximum temperatures near **31.6–32.4°C** for the hottest June entries, while recent public reporting has shown individual days reaching the mid-30s, including **36.1°C** in a past record heat event[3][2].

The catalysts to watch are straightforward: the daytime forecast, any very hot weather warnings, and the timing of the Observatory’s daily climate publication, because that final extract determines settlement, not live headlines. Hong Kong Observatory data pages note that climate figures are compiled from official recorded temperatures, and the monthly weather summary archive is the relevant place to check when the 21 June entry is finalised[4][8]. For programmatic trading, that means polling the Observatory source on a schedule, validating the decimal-range bucket against the published value, and only then triggering any copy-trade or conditional-order logic.

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). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket App UK, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket App UK is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

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?

Not under $1,500 of lifetime trading volume. Above that threshold, Polymarket App UK triggers a quick verification flow that finishes in minutes.