Highest temperature in Shanghai on August 21?

Platform comparison

Market context

Polymarket has this Shanghai temperature contract at 0% YES, which leaves the market effectively priced for the lower bands rather than a late-day spike. The settlement source is the Daily Observations table at Weather Underground for Shanghai Pudong International Airport, with the highest temperature on 21 August 2026 deciding the outcome in Celsius before the 12:00 UTC settlement window closes.

The current forecast backdrop points to a warm but not extreme day. Recent outlooks for Pudong cluster around the high 20s to low 30s Celsius, with one forecast showing about 32°C and patchy rain, while another has 88°F with afternoon rain and a possible thunderstorm later in the day; that profile would usually keep the top reading near the low-30s bands rather than pushing into a much hotter range.[1][2][3] For a trader holding USDC on Polygon through the conditional-token market, the practical read is that the contract is living off weather-model drift, not a clear heat event.

Historical Shanghai summer patterns still matter because the city can swing from muggy, storm-prone highs to sharper heat under subtropical high pressure. Earlier August coverage noted heatwave conditions with 35-38°C daytime peaks, but the more relevant comparable case for this market is whether convection or cloud cover suppresses the airport station’s maximum during the observation window.[4] The main catalysts are the latest airport-specific forecast updates, any shift in rain timing, and the exact Daily Observations reading at Pudong, since that source, not the summary high-low line, controls settlement.[1][2][3]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in Shanghai on August 21? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to PolyGram, which mirrors the Polymarket order book at 0% fees.

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 PolyGram. 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'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.

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.