Highest temperature in Hong Kong on July 21?

Platform comparison

Market context

Hong Kong faces its peak summer heat on 21 July 2026, as the Hong Kong Observatory records the day’s absolute maximum temperature in degrees Celsius to settle a weather prediction contract. The market currently shows a 0% crowd-implied probability for the YES outcome, suggesting traders expect the temperature to fall outside the specific range offered, despite seasonal forecasts indicating normal to above-normal temperatures for July through September 2026 due to prevailing ENSO conditions[2].

Historical data from previous July highs in Hong Kong typically ranges between 31°C and 35°C, with extreme heatwaves occasionally pushing readings above 36°C. The zero probability assigned to the YES side diverges sharply from the seasonal outlook, which anticipates warmer-than-average conditions, creating a notable gap between prediction-market implied odds and the climate model consensus that suggests above-normal heat is likely[2]. Sportsbooks covering similar weather events often price in higher volatility for summer peaks, whereas this contract appears to underweight the probability of a heat spike.

Traders should monitor the Hong Kong Observatory’s daily extract for the finalized “Absolute Daily Max” figure, which will determine settlement once published after the 12:00 UTC deadline. No immediate announcements or schedule changes are expected, but the final resolution depends entirely on the Observatory’s official data release, which may lag slightly behind real-time conditions. The market remains inactive until this specific dataset is confirmed, meaning no catalysts other than the official publication will shift the odds before settlement[1].

Sources: 1 · 2

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 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.

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 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.