Highest temperature in Hong Kong on July 5?

Platform comparison

Market context

The real-world event at stake is the highest air temperature recorded by the Hong Kong Observatory on 5 July 2026, measured in degrees Celsius to one decimal place. This market resolves to the temperature range containing that peak reading, with data finalised in the Observatory’s Daily Extract. The current crowd-implied probability of 0% for a “YES” outcome suggests traders believe the temperature will fall outside the specific range being wagered on, though historical patterns indicate July in Hong Kong is consistently hot.

Historical data frames this probability sharply: July 2007 saw the highest monthly mean maximum temperature of 32.9°C at the Observatory headquarters, while recent years show a warming trend of 0.35°C per decade since 1996[9]. In 2025, Hong Kong recorded 53 very hot days and 54 hot nights, ranking third highest on record, with peak temperatures reaching 35.7°C at Tsim Sha Tsui[10]. Even in 2023, Sheung Shui hit 39°C on the hottest July day, far exceeding typical Observatory headquarters readings[3]. These comparable cases suggest that a 0% implied probability may reflect an overly narrow range rather than a lack of heat.

Traders should monitor the Observatory’s daily climatological updates and any extreme weather advisories issued by the Hong Kong Government, as sudden shifts in monsoon activity or urban heat can alter peak temperatures. The resolution depends entirely on the finalised “Absolute Daily Max” entry in the Daily Extract, which is only published after data validation[4]. Recent reports confirm July 2026 is forecast to see daily highs between 30.6°C and 35°C in Sha Tin, with overnight lows near 27°C[6]. Any divergence between sportsbook lines on similar heat contracts and this prediction market’s 0% implied probability warrants scrutiny, especially given analyst consensus that July remains Hong Kong’s hottest month on record[5].

Sources: 1 · 2 · 3 · 4 · 5

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

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 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 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.