Highest temperature in Guangzhou on July 4?

Platform comparison

Market context

The real-world event is the peak daytime heat at Guangzhou Baiyun International Airport on 4 July 2026, where the highest recorded temperature will determine the market outcome. With the crowd-implied probability for a 31°C hit sitting at 0%, the consensus firmly treats this as an underdog scenario, assuming the heat will fall short of that threshold. Historical climatology frames this probability as deeply misaligned; July is Guangzhou’s hottest month, with average daily highs consistently ranging between 33°C and 35°C, rarely dipping below 30°C [1][3]. Recent records show the city’s hottest day reached 39°C in late July 2024, while typical daily highs hover around 33°C (91°F), making a sub-31°C reading an extreme outlier rather than a standard expectation [5][9].

Traders should watch for immediate catalysts including the morning weather briefing from the China Meteorological Administration and any sudden shifts in the subtropical ridge that governs regional heat [6]. The settlement depends entirely on the Wunderground record for the Baiyun station, so any localised cloud cover or unexpected rain showers before noon could act as a contrarian angle against the 0% consensus [4]. While the national trend shows China recorded its hottest month in recent history in July 2024, reinforcing the likelihood of extreme heat, the specific value spot lies in betting against the 0% probability, as the historical data suggests a 31°C hit is not just possible but statistically probable [6][7]. The underdog here is the market’s assumption of coolness, not the heat itself.

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

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'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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 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.