Highest temperature in Guangzhou on July 9?

Platform comparison

Market context

On 9 July 2026, the highest temperature recorded at Guangzhou Baiyun International Airport will determine the outcome of a prediction market where the crowd currently assigns a 0% probability to the “YES” side. This implies the market believes the temperature will fall outside the specified range, yet historical data suggests early July in Guangzhou typically sees daily highs between 31°C and 34°C[4]. The city has recently experienced its longest summer since 1961, with average July temperatures reaching 23.3°C—the highest since 1961[2][6]. Such sustained heat waves indicate that temperatures exceeding 31°C are not only plausible but increasingly common, challenging the consensus view that the range is unreachable.

Traders should monitor real-time updates from Wunderground, the official resolution source, particularly as Guangzhou continues to break heat records[3]. Recent reports confirm the city has surpassed a three-decade heat threshold, with 235 summer days recorded by temperature alone[8]. The key catalyst is whether the heatwave persists through 9 July, as early July highs have historically clustered firmly within the 31–34°C band[4]. Contrarian value may lie in betting “YES” if the market underestimates the momentum of this unprecedented warming trend, especially given that the crowd-implied probability of 0% appears to ignore the city’s record-breaking thermal trajectory[2]. The underdog here is the “NO” side, which assumes a temperature drop despite overwhelming evidence of sustained high heat.

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.

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.

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.