Highest temperature in Shanghai on August 18?

Platform comparison

Market context

Shanghai's highest temperature on 18 August 2026 will be recorded at Pudong International Airport Station and resolved against the Daily Observations table on Weather Underground. The market currently shows 0% implied probability across the crowd, suggesting either extreme confidence in a specific temperature range or insufficient liquidity to establish meaningful odds.

August temperatures in Shanghai historically cluster between 32–36°C, with occasional peaks above 37°C during heat waves. The city's summer climate is driven by the East Asian monsoon and the influence of the Western Pacific subtropical high-pressure system. Over the past decade, mid-August highs have ranged from 29°C in cooler years to 38.9°C during the 2013 heat event. The 0% crowd probability likely reflects traders positioning around a narrow band rather than genuine uncertainty about whether temperatures will fall within Shanghai's typical August envelope. Comparable weather markets on Kalshi and Polymarket show similar clustering patterns when resolution hinges on precise temperature bands rather than binary outcomes.

Traders should monitor seasonal forecasting updates from the China Meteorological Administration, typically issued in early August, which provide 10–15 day outlooks for the Yangtze River Delta region. The El Niño/La Niña cycle and tropical cyclone activity in the Western Pacific during mid-August could shift conditions materially. Any tropical system approaching eastern China in the week prior would suppress temperatures and increase cloud cover, whilst a stalled high-pressure system would sustain heat. Real-time atmospheric indices and satellite imagery from late July onwards will clarify whether August 2026 tracks toward the warmer or cooler end of Shanghai's historical range.

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

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.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like PolyGram 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.