Highest temperature in Shanghai on July 1?

Platform comparison

Market context

The underlying event is the peak temperature recorded at Shanghai Pudong International Airport on 1 July 2026, measured in degrees Celsius. Historical data confirms July is the hottest month at this station, with average highs reaching 31°C (87°F) and daily peaks rarely falling below 24°C (75°F) or exceeding 35°C (95°F)[1][3]. Summer conditions regularly exceed 30°C, often climbing to 35°C during the most sunny intervals[8]. Given this consistent thermal baseline, a market implying 0% probability for any temperature range is statistically anomalous, suggesting a potential data error or mispricing rather than a genuine meteorological expectation of freezing conditions.

A power-user approaching this programmatically would script a scraper to pull Wunderground’s hourly history for ZSPD, validating the 12:00 UTC settlement window against real-time sensor feeds[2]. The primary catalyst to monitor is the onset of the East Asian summer monsoon, which dictates cloud cover and precipitation; a sudden shift to heavy rain could suppress peaks below 30°C, though such an event remains rare in early July. Recent forecasts for July 2026 indicate daily highs between 27°C and 34°C, reinforcing the likelihood of temperatures well above freezing[6]. Traders should also watch for official heatwave advisories from Chinese meteorological authorities, which often precede record-breaking days, as these dependencies directly influence the resolution source’s final value.

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

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.

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.

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.

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.