Highest temperature in Shanghai on August 18?

Platform comparison

Market context

Shanghai's daily maximum temperature on 18 August 2026 will be measured at Pudong International Airport Station and reported in Weather Underground's Daily Observations table. The market resolves to whichever temperature band contains that recorded high, with the Daily Observations data taking precedence over any summary figures. This distinction matters for programmatic resolution: traders building automated monitoring systems should query the granular observations endpoint rather than relying on cached day-high summaries, which occasionally lag or round differently.

August in Shanghai typically sees highs between 32–35°C, with occasional peaks above 36°C during heat waves. Historical data from the past five years shows that extreme temperatures (above 38°C) occur roughly once every two to three years in mid-August, whilst readings below 30°C are rare. The 0% crowd probability suggests the market may be pricing in either a specific temperature threshold that is genuinely unlikely, or reflects low liquidity and sparse trading activity. Comparing against Shanghai's August climatology and recent seasonal patterns will help calibrate whether that probability reflects genuine scarcity or mispricing.

Traders monitoring this market should track China Meteorological Administration forecasts and any typhoon activity in the Western Pacific during early-to-mid August 2026, as tropical systems can suppress temperatures significantly. Real-time feeds from Weather Underground's API allow conditional orders to trigger based on forecast updates or observed readings from comparable stations. Settlement occurs at midday UTC on 18 August, giving traders a window to adjust positions based on morning observations from Shanghai itself.

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 Kalshi Fees. 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 Kalshi Fees 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.