Highest temperature in Hong Kong on July 21?

Platform comparison

Market context

Hong Kong will record its highest temperature on 21 July 2026, a single data point the Hong Kong Observatory will publish as the “Absolute Daily Max” in degrees Celsius to one decimal place. On Polymarket, this contract trades with the YES outcome at 0% implied probability, meaning the crowd prices a near‑zero chance that the market’s chosen temperature range will be hit, while USDC shares on Polygon settle only once the Daily Extract is finalized.

Historically, mid‑July in Hong Kong is hot and humid, with daily maxima often between 31°C and 35°C, and absolute records in the 36°C–37°C band during heatwaves influenced by the subtropical ridge and weak tropical activity. The current 0% price suggests traders expect the actual maximum to fall outside the listed range, consistent with recent summers where peak readings clustered around 33°C–34°C rather than the extremes needed to trigger YES, as reflected in the Observatory’s climatological summaries [1].

Traders should watch the Observatory’s Daily Extract release schedule for 21 July, which is the sole dependency for settlement, and monitor any mid‑month weather bulletins on the subtropical ridge position or incoming tropical disturbances that could push maxima higher. There are no public announcements tied to this date yet, but the resolution source is fixed: once the Daily Extract is published, the market cannot resolve until that data is finalized, making the extract’s timing the key catalyst for price movement [1].

Sources: 1

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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

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 Scam? 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.