Highest temperature in Hong Kong on July 31?

Platform comparison

Market context

Hong Kong’s weather on 31 July is the real-world event behind this contract, with settlement tied to the Hong Kong Observatory’s final “Absolute Daily Max” figure for the day. The current crowd-implied probability of **0% YES** is far below what would usually be associated with a hot, midsummer afternoon in Hong Kong, so the contract is effectively pricing in an outcome below the relevant temperature band or a belief that the specific band selection is very unlikely to be hit.

Historically, July in Hong Kong sits in the peak heat season, with the Observatory’s own climate pages and month-ranking pages showing that extreme temperatures in the mid-30s Celsius are well within the city’s summer range. Recent reporting also underlines how often the Observatory has recorded the year’s hottest readings in late July, including 36.1°C on 27 July 2023 and 31.6°C on a more recent hottest-day update, which is a useful reminder that the upside tail is material even if the most common outcome is lower. In that context, a zero-priced YES line looks much more like a market expression of contract mechanics or mispricing than a view that Hong Kong cannot get warm enough on the day.

The main catalyst is the Observatory’s daily extract publication, because this market cannot resolve until the final data for 31 July has been posted. Traders are therefore watching the intraday weather pattern, any late-afternoon heat spike, and the timing of the Observatory’s update, rather than a conventional news event. On a cross-platform basis, the key comparison is whether sportsbook-style temperature bands, prediction-market pricing, and weather-model consensus all point to the same approximate peak; if they do not, the widest gaps usually come from different settlement rules and the fact that this contract depends on one official maximum reading rather than a citywide average.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Hong Kong on July 31? 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 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 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 Best Prediction Markets trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.