Highest temperature in Guangzhou on August 4?

Platform comparison

Market context

Guangzhou’s airport should post another hot, humid August day, and the market is effectively asking whether the day’s high gets above the low-30s Celsius range. The crowd-implied probability of **0% YES** leaves the **under** as the clear favourite, with any upside case needing a clean break into unseasonably strong heating at Baiyun Airport rather than the more routine monsoon pattern.

That pricing sits against a fairly sturdy historical backdrop: August is one of Guangzhou’s hottest months, with forecast norms commonly centred around highs in the low 30s Celsius and frequent rain or showers that can cap daytime peaks.[1][3][15][16] For 4 August specifically, published outlooks have clustered around roughly **33°C** highs with showers, while another model has even lower day-ahead values near **32°C** and heavy rain risk.[2][12] In handicapper terms, consensus is already leaning to a typical warm, wet outcome, so the value question is not whether it gets hot, but whether the airport’s observed maximum can push materially above the market’s implied zero-probability threshold.

For catalysts, the main watches are the evolution of rain bands, cloud cover and timing of afternoon convection, because these are the factors most likely to suppress the daily maximum or, if showers clear early, allow a late spike in temperature.[2][12][17] Guangzhou’s day is also sensitive to humidity and light winds, which can keep it oppressive without necessarily lifting the maximum as much as the market might expect.[7][12][18] The settlement source is the Baiyun Airport station on Wunderground, so any intraday swing will come down to the actual observed high there, not the city average or forecast high elsewhere.

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

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 Who Will Win. 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.

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.

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.