Highest temperature in Hong Kong on August 2?

Platform comparison

Market context

Polymarket is pricing this Hong Kong temperature contract at the low end of the August range, with **27°C** leading at **34%** and **28°C** close behind at **32%**. On Polymarket, traders post and buy **USDC** positions on **Polygon**, and the winning **conditional tokens** will redeem for $1 once the Hong Kong Observatory’s final daily extract is available. The market is therefore about the Observatory’s recorded **absolute daily maximum**, not forecasts, and it will only settle after the official data for 2 August is published. [1]

For context, Hong Kong’s August climate usually sits in the high 20s to low 30s Celsius, so a 27–28°C outcome is not an outlier if cloud, rain, or an onshore flow suppresses the day’s peak. The current 0% crowd-implied chance for the market as a whole reflects the fact that the contract is being read through a multi-outcome grid, not as a binary event. Recent Hong Kong coverage shows how quickly the city can swing from ordinary summer heat to the year’s hottest reading, with local reports this season citing 34.3°C and even 35.6°C as the Observatory’s highest daily maxima to date, which is a reminder that upper-tail outcomes remain plausible when conditions turn clear and hot. [4][12][13]

The main catalysts are the Observatory’s day-of weather updates, rain or thunderstorm warnings, and the timing of the final “Daily Extract”, because the market cannot resolve until that publication appears. Traders watching the board should also pay attention to the official Hong Kong regional weather readouts and any short-term forecast shifts in the hours before the settlement window closes, as a small change in cloud cover or rainfall can move the day’s maximum by a full degree. The settlement source is the Hong Kong Observatory’s daily climate record, so the final figure matters more than intraday extremes or media headlines. [2][3]

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 Polymarket Alternative UK. 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 Polymarket Alternative UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.