Highest temperature in Hong Kong on June 27?

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Market context

The real-world event is the highest temperature recorded by the Hong Kong Observatory on 27 June 2026, with the market currently implying a 0% chance of a "YES" outcome for any specific range, despite ensemble forecasts suggesting seasonal norms of 30–32°C. Historical data frames this probability tightly: late June in Hong Kong typically sees highs near 30–32°C as the summer monsoon arrives, with recent years showing ranges like 27–31°C and humidity often exceeding 80%[3][7]. While a record-breaking heatwave pushed temperatures to 36.1°C earlier this year, such extremes are outliers against the consistent backdrop of 30–31°C being the most probable band for late June[1][4]. The consensus heavily favours the 30°C range at 67%, with 29°C as the next likely spot at 21%, leaving the 31°C and 32°C ranges as underdogs with minimal support[1].

Traders should watch the Hong Kong Observatory’s "Daily Extract" for the finalized "Absolute Daily Max" data, as the market cannot resolve until this official figure is published[1][9]. The immediate catalyst is the rain forecast for 27 June, which predicts significant rainfall with a 75–95% probability, potentially suppressing temperatures below the seasonal 30°C average[3]. Recent news highlights that while extreme heat warnings have been issued for other days, the specific forecast for 27 June points to rain, creating a contrarian angle where the market’s 0% implied probability might undervalue the chance of a cooler day if the rain intensifies[3][8]. The value spot likely sits in the 29°C or lower ranges if the monsoon rain delivers as forecast, challenging the consensus that 30°C is the frontrunner.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Hong Kong on June 27? 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

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 Who Will Win, 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?

Who Will Win 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 does it cost to trade on Who Will Win?

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

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Who Will Win triggers a quick verification flow that finishes in minutes.