Lowest temperature in Hong Kong on August 8?

Platform comparison

Market context

Hong Kong’s overnight low on 8 August will be set by the Hong Kong Observatory’s final “Absolute Daily Min” reading, with the contract resolving only after that Daily Extract is published and finalised. The current crowd-implied **0% YES** sits against a process that is data-driven rather than judgement-based: once the Observatory posts the completed value in Celsius to one decimal place, the range outcome is mechanical, not interpretative.

The historical framing is straightforward. The Observatory’s August normals put the month’s mean minimum at **26.9°C** on 8 August, with the mean temperature at **29.0°C**, which suggests that very low outcomes are uncommon but not impossible in the climatological sense. Broader August summaries from weather sites cluster typical lows around **26–27°C**, and one historical compilation cites a record August low of **19.2°C**, showing that the tail exists even if it is far from the centre of the distribution. That makes a zero-priced YES line look like the market is treating the contract as effectively a near-certainty for the non-YES side rather than reflecting any narrow weather range.

For catalysts, traders should watch the Hong Kong Observatory’s hourly readings, the morning weather bulletin, and the timing of the final Daily Extract, because the market cannot settle until the day’s data are published. At 3 a.m. Hong Kong time, the Observatory reported **29°C** at the station, with nearby sites mostly in the **27–30°C** band, which is consistent with a warm start and reduces the likelihood of a very low final minimum unless a later pre-dawn dip emerges. Any divergence between sportsbook-style odds, prediction-market pricing, and analyst consensus would likely hinge on how aggressively each venue weights that overnight temperature profile against Hong Kong’s seasonal August baseline.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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 Best Prediction Markets. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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 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.

Do I need to KYC for this market?

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