Highest temperature in Shanghai on August 4?

Platform comparison

Market context

Shanghai’s airport temperature is expected to finish well above freezing and firmly in summer territory, which makes the current 0% YES market price look far below both climatology and live forecasts. AccuWeather’s August outlook for Shanghai puts daily highs mainly between 82°F and 92°F, while other August guides cluster around 31–34°C, and a day-specific forecast for 4 August points to a high near 34°C with no meaningful rain signal[1][3][7][8][10]. On that basis, the contract’s implied probability appears to be pricing either an obvious misread of the settlement mechanics or a market that has not yet attracted informed participation; there is no visible sportsbook-style line in the supplied sources to anchor a formal cross-market divergence, but the weather outlook itself is clearly consistent with a positive settlement outcome[1][3][7].

Historically, early-August Shanghai weather is often hot, humid and prone to afternoon peaks rather than mild daytime ceilings, so the relevant comparison is not whether the city gets warm, but whether the airport record for the day clears the contract’s band. Forecasts now call for daytime maxima around 33–34°C and very high humidity, with only light wind and limited precipitation, conditions that typically support a higher daily maximum if cloud cover stays broken[2][3][15]. The main trader watch-items are therefore updates to the short-range forecast, especially any shift in cloud, rainfall or typhoon-adjacent moisture that could suppress the afternoon high, plus the daily observational feed from Shanghai Pudong International Airport Station that Wunderground uses for settlement[2][3]. If later runs hold near the current 33–34°C range, analyst consensus is much closer to a high-temperature YES than to the market’s 0% implied pricing[2][3][15].

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 Best Prediction Markets. 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 Best Prediction Markets 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.