Lowest temperature in Hong Kong on July 31?

Platform comparison

Market context

Hong Kong’s overnight low on 31 July is the real-world anchor here, and the market’s **3% YES** price makes the under on the stated range the heavy favourite. In practical terms, the consensus is for a warm, summer-night outcome rather than an unusually cool one: official forecasts for 31 July put Hong Kong around **27–31°C** or **28–32°C**, with showers and thunderstorm risk but no sign of a marked cold intrusion.[2][6] That leaves any outcome requiring a notably low minimum as a contrarian play, especially once the observation is tied to the Observatory’s final daily extract rather than a generic city forecast.[3][10]

Historically, late-July Hong Kong nights sit deep in the humid season, with average lows typically in the high 20s Celsius and July weather described as hot, cloudy and rainy rather than cool.[1][14][17][18] That framing matters for handicapping: the favourite is the band around the low-to-mid 20s, while a YES on a genuinely low reading needs a wetter, cloudier or storm-affected setup that suppresses the minimum temperature. The current 3% implies the crowd is treating a low-end reading as a tail event; if the settlement band is broad enough to catch a standard tropical-season minimum, there may be less value in chasing the longshot.

The main catalysts are the Hong Kong Observatory’s own daily forecasts and, more importantly, the final published “Daily Extract” after the day closes, because that is the source that resolves the market.[3][10] On the day itself, the Observatory’s forecast called for unsettled weather, showers and thunderstorms, with a thunderstorm warning also in force early on 31 July, which can matter more for how the temperature bottoms out than for the daytime high.[2][11] Traders should watch whether showers persist into the evening and overnight, since cloud cover and rain can hold up the minimum, but there is no dependency here on any separate announcement beyond the Observatory’s final archived observation.[2][3]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Lowest temperature in Hong Kong on July 31? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Who Will Win, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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 Who Will Win. 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.