Highest temperature in Hong Kong on August 4?

Platform comparison

Market context

Polymarket currently has this contract pricing the top outcome at **30°C** around 40%, with **29°C** close behind at 34%, so the crowd is leaning towards a hot but not extreme afternoon in Hong Kong. On Polymarket, positions are funded in **USDC** on **Polygon**, and the winning temperature band settles against the Hong Kong Observatory’s published **Absolute Daily Max** for 4 August, with shares in the correct bucket redeemable for $1 once the data is finalised. [1]

The historical frame matters because Hong Kong’s August highs often sit in the upper 20s to low 30s, but the city regularly sees excursions above 34°C in late-summer heatwaves. Recent reporting from local outlets showed Hong Kong reaching **34.6°C** and later **35.6°C** during this summer’s hottest spells, which is enough to keep the upper end of the market in play even if the modal expectation remains closer to 30°C. [8][9][13]

A trader watching this market should focus on the Hong Kong Observatory’s daytime forecasts, any thunderstorm or typhoon warnings, and whether the daily extract is updated with a final maximum after the observation window closes. The settlement source is the Observatory’s climatological daily extract rather than an intraday headline temperature, so the key dependency is the official final **one-decimal Celsius** reading rather than the live market maximum seen during the day. [1][12][17]

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 PolyGram. 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.

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.