Highest temperature in Chengdu on July 20?

Platform comparison

Market context

The market tracks the peak temperature recorded at Chengdu Shuangliu International Airport on 20 July 2026, with settlement based on Wunderground data. Despite the crowd-implied probability for a specific outcome sitting at 0%, Polymarket data shows a stark divergence: the frontrunner is 38°C at 100% probability, while the next closest outcome, 34°C or below, holds 0% [1]. This massive discrepancy between platforms suggests a potential pricing error or liquidity gap rather than a genuine consensus on cool conditions.

Historical July weather in Chengdu typically sees maximums around 31°C with 75% relative humidity, often described as boisterous and very warm [2]. While rain is frequent, with a 50% daily probability, extreme heatwaves pushing temperatures to 38°C are less common than the 31°C average but remain plausible during summer peaks. The current 0% implied probability for the market’s primary question contradicts the historical likelihood of high temperatures, whereas the 100% Polymarket line on 38°C aligns more closely with the upper bounds of seasonal extremes [1][2].

Traders should monitor the daily weather forecast for the rainy season, as sudden shifts in precipitation could suppress peak temperatures below the 38°C threshold [3]. Key catalysts include official announcements from Chinese meteorological services regarding summer heatwaves and school holiday crowd impacts, which may influence local atmospheric conditions. The settlement window closes on 20 July 2026 at 12:00 UTC, meaning real-time Wunderground updates for ZUUU will be the sole resolution source [1].

Sources: 1 · 2 · 3

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

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

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.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Best Prediction Markets trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.