Lowest temperature in Hong Kong on August 5?

Platform comparison

Market context

Polymarket is pricing this Hong Kong minimum-temperature contract with the **27°C** bucket at about **96%**, while **26°C** sits near **5%**, so the market is treating an unusually cool reading as remote and a standard summer overnight low as the base case. On Polymarket, traders are buying and selling USDC-denominated conditional tokens on Polygon, so the quote reflects a live probability rather than a forecast headline; if the Hong Kong Observatory’s published “Absolute Daily Min (deg. C)” for 5 August falls into the correct range, the winning token redeems for $1.

That pricing is consistent with Hong Kong’s summer climatology, where early August daily minimums commonly sit in the high 20s and the Observatory’s own normals put 5 August’s mean minimum at 26.8°C. Comparable recent extremes show that the city can briefly cool when rain is persistent: the Observatory reported a minimum of 24.0°C on 5 August 2025 and 24.9°C on 5 August 2020, both during wet spells. Those cases frame the tail risk here, but they also underline how unusual it is for Hong Kong to print a materially lower overnight low in midsummer.

The main catalysts for traders are not market chatter but the Observatory’s data publication cadence and any late revisions to the Daily Extract, since Polymarket says only the initially published figure for the market window counts. The contract cannot resolve until the 5 August extract is finalised, so the practical watchpoint is the Hong Kong Observatory climatology page rather than forecasts after the fact. If rain or a tropical disturbance had materially changed overnight conditions, that would matter for the underlying reading, but once the official extract is locked, the on-chain position settles mechanically through the conditional-token framework.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Lowest temperature in Hong Kong on August 5? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is PolyGram. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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 Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.