Highest temperature in Hong Kong on June 25?

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Market context

The underlying event is the highest temperature recorded by the Hong Kong Observatory on 25 June 2026, measured in degrees Celsius to one decimal place. Current crowd-implied probability of 0% YES suggests the market expects the temperature to fall outside the specific range being traded, likely due to anticipated weather shifts. Historical data frames this probability: June 2016 saw the highest monthly mean maximum of 32.4°C, while recent days in June 2026 hit 34.6°C, yet the Observatory warns of a dramatic cooling trend[2][3]. The forecast indicates a broad trough of low pressure will bring nine consecutive days of rain, with temperatures dropping to a cooler 26–30°C range by Sunday and Monday, making extreme heat on 25 June unlikely[2].

A power-user approaching this programmatically must monitor the Hong Kong Observatory’s "Daily Extract" for the finalized "Absolute Daily Max" value, as the market cannot resolve until this data is published[2]. The primary catalyst is the imminent arrival of severe weather, including squally thunderstorms and hail, which the Observatory explicitly flagged as starting this weekend[2]. Traders should watch the UV Index forecast, which remains very high (index 10) for 25 June, but the overriding dependency is the low-pressure trough moving over southern China, which will suppress temperatures significantly[2][10]. Recent news confirms the extreme heat is rapidly giving way to wet weather, with heavy showers peaking on Sunday and Monday, directly contradicting any scenario of record highs on 25 June[2].

For conditional order strategies, the key is the timing of the data release in the "Daily Extract," which determines the settlement. The market’s 0% probability aligns with the meteorological consensus that the nine-day rain event will have already cooled the city by 25 June[2]. Any automated bot must ingest the Observatory’s real-time updates, noting that the current 32.7°C reading at 17:40 HKT is already a fraction of the earlier 34.6°C peak, confirming the cooling trend[6][9]. The settlement window ending 2026-06-25T12:00:00Z requires precise alignment with the finalised data, ensuring no trade is executed before the "Daily Extract" is available[2].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Hong Kong on June 25? 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 PolyGram, 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.

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 PolyGram?

Zero. PolyGram 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.

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.