Highest temperature in Hong Kong on August 3?

Platform comparison

Market context

Hong Kong’s official high temperature on 3 August will settle against the Hong Kong Observatory’s one-decimal Celsius reading, so the market is effectively asking where the day’s peak lands within a narrow band rather than whether it will be hot or cool. With the crowd-implied probability still at 0% for the generic “YES” framing, the contract appears to be trading as a pure range view, and the live market pricing on Polymarket is concentrated in the mid-to-high 20s rather than the low 30s.[2][7]

That sits below Hong Kong’s recent summer extremes. The Observatory has already logged several very hot days this year, including a 34.3°C high reported in mid-July and earlier readings above 35°C in local press coverage, which shows that outlier heat is possible even if it is not the base case on any given day.[9][13] For August specifically, third-party climate guides still point to typical highs around 27°C–32°C, so the market’s centre of gravity near 27°C and 28°C is consistent with a normal-to-mildly warm outcome rather than a heat-spike scenario.[12][2]

The main catalysts are the Observatory’s same-day observations, the midday and afternoon evolution of cloud, rain and local showers, and any late updates to the daily extract that feeds settlement. Polymarket notes that revisions after initial publication will not count, so traders usually care most about the first finalized “Absolute Daily Max” entry for the day rather than later corrections.[2][7] In practice, the biggest cross-platform divergence to watch is between sportsbook-style weather pricing, which tends to reflect point forecasts, and the prediction-market distribution, which is already concentrating probability across adjacent bins rather than a single exact temperature.[2][3]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Hong Kong on August 3? 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

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.

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.

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.