Highest temperature in Hong Kong on June 25?

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Active sub-markets

Market context

On 25 June 2026, Hong Kong will face its peak daily heat, with the Hong Kong Observatory recording the absolute maximum temperature in degrees Celsius. This real-world event determines the market outcome, where the crowd currently assigns a 0% probability to the “YES” side, implying near-certainty that the temperature will fall outside the specified range.

Historical June data frames this improbability: recent years show daily highs typically between 30°C and 35°C, with the hottest day of 2026 so far reaching 34.6°C [5]. Long-term averages suggest a mean high of 30°C [6], while seasonal forecasts for June–August 2026 predict above-normal temperatures [2]. Platforms diverge sharply here: Polymarket displays implied probability (0%), whereas Kalshi and Betfair use decimal odds, and fee structures and KYC requirements vary significantly across these books.

Traders should monitor the Observatory’s Daily Extract releases, which finalise the “Absolute Daily Max” data after the settlement window ends on 25 June 2026 at 12:00 UTC. Recent extreme heat warnings from the Observatory, including a 33.7°C peak earlier in June [4], signal rising volatility. Smarkets and Betfair may offer deeper liquidity for such weather-dependent events, but their decimal odds format requires recalibration compared to Polymarket’s probability-based interface. Always verify the official source before resolving positions.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in Hong Kong on June 25? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live quote comes directly from the Polygon order book; the other three are listed with their platform attributes — fees, KYC, settlement currency, payment options — because a 1:1 contract comparison without API access would be guesswork.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket Alternative, 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 Polymarket Alternative?

Zero. Polymarket Alternative 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, Polymarket Alternative triggers a quick verification flow that finishes in 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.