Highest temperature in Hong Kong on June 21?

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Market context

Hong Kong’s hottest reading on 21 June will be set by the Hong Kong Observatory’s **Absolute Daily Max** for the day, with settlement tied to the final published extract rather than an intraday print. The market is currently pricing **0% YES**, which is a clear divergence from the weather itself: summer-solstice heat in Hong Kong has repeatedly reached the mid-30s, including 34°C on 21 June in a recent comparable case and 36.1°C on another very hot day this year, showing that extreme outcomes are not rare in this climate.[8][1]

That backdrop matters because June in Hong Kong has a well-established warm baseline. The Observatory’s June climatology shows historically high monthly mean maximum temperatures, with the warmest June average maximum at 32.4°C and several other Junes close behind, so a daily peak above 33°C is entirely plausible when heat builds under a subtropical ridge.[2] The Observatory also notes a long-run warming trend of 0.35°C per decade over 1996–2025, which supports the view that very hot June days are becoming more common rather than exceptional.[9]

For traders, the key catalysts are the day’s weather evolution and the Observatory’s final reporting timetable, not a pre-market narrative. The contract cannot resolve until the HKO publishes the relevant Daily Extract, and the settlement window closes at 12:00 UTC, so late-day observations and post-midday updates are what matter most.[7] With no sportsbook-style line evident in the materials provided, the comparison point is mainly the near-zero prediction-market price versus the historical frequency of low- to mid-30s maxima in Hong Kong’s June heat.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Hong Kong on June 21? on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

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

Is this market available outside the US?

Best Prediction Markets 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.

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 it cost to trade on Best Prediction Markets?

Zero. Best Prediction Markets routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.