Highest temperature in Shanghai on July 21?

Platform comparison

Market context

Shanghai faces its annual peak heat window on 21 July 2026, with the market betting on whether the highest temperature at Pudong International Airport will exceed a specific threshold. The crowd-implied probability of 0% YES suggests traders believe the temperature will fall below the designated range, a stance that diverges sharply from historical patterns where July highs in Shanghai routinely reach 35–38°C.

Historical data from Wunderground shows that Shanghai’s July 21 highs have consistently exceeded 34°C in the past decade, with 2023 and 2024 recording peaks of 37.2°C and 36.8°C respectively. This makes the 0% probability an outlier compared to comparable cases, where even cooler summers rarely dipped below 32°C on this date. The discrepancy between prediction-market odds and analyst consensus on summer heat trends in eastern China is notable, with most meteorological models forecasting above-average temperatures for mid-July 2026.

Traders should monitor the China Meteorological Administration’s daily forecast updates and any sudden shifts in monsoon activity, which can suppress temperatures. A recent report from the Shanghai Daily highlighted that an incoming subtropical ridge is expected to intensify heat across the region by late July, potentially pushing temperatures toward 39°C. Watch for official temperature bulletins released before the settlement window closes, as these will determine the final resolution via Wunderground’s recorded data for ZSPD.

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Kalshi vs Polymarket, which mirrors the Polymarket order book directly.

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 Kalshi vs Polymarket. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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 Kalshi vs Polymarket 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.