Highest temperature in Hong Kong on July 21?

Platform comparison

Market context

On 21 July 2026, the Hong Kong Observatory will record the day's highest temperature in degrees Celsius. That reading, to one decimal place, will fall into one of several temperature bands offered on Polymarket. The contract currently prices at 0% across all outcome ranges, reflecting either sparse liquidity or a settlement delay—the market cannot resolve until the Observatory publishes its daily extract data, which typically arrives within days of the observation date but occasionally faces administrative lag.

Hong Kong's July temperatures cluster reliably between 29°C and 34°C, with extreme heat days occasionally breaching 35°C. Historical records show that mid-to-late July sits near the annual peak for daily maxima, though the range varies considerably year-on-year depending on monsoon patterns and tropical cyclone activity. The 2023 summer saw multiple days exceed 33°C in July; 2022 was comparatively cooler. Traders should reference the Observatory's climate statistics portal, which publishes thirty-year normals and recent seasonal trends, to calibrate expectations against the specific outcome bands available.

The primary catalyst affecting this market is the East Asian summer monsoon's strength and timing in mid-2026. Tropical cyclone activity in the Western Pacific during June and early July will shape atmospheric circulation patterns that determine whether Hong Kong experiences typical summer heat or anomalously warm conditions. The Hong Kong Observatory issues seasonal forecasts and updates its extended outlook monthly; these publications, alongside real-time weather alerts issued during the settlement window, will provide the most concrete signals for traders positioning before 21 July.

Methodology

We track Highest temperature in Hong Kong on July 21? 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

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 Kalshi UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

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