Highest temperature in Paris on July 12?

Platform comparison

Market context

The market tracks the peak temperature at Paris-Le Bourget Airport on 12 July 2026, with the settlement window closing at noon UTC. Current crowd-implied probability sits at 0% for any outcome, yet Polymarket data shows the leading outcome is 35°C at 92%, suggesting the 0% figure reflects a technical display error or a specific binary sub-market rather than the full range consensus [1]. Programmatic traders should script queries against the Wunderground daily history endpoint for LFPB to automate resolution checks, bypassing manual interface toggles between Celsius and Fahrenheit.

Historical context frames the 35–37°C consensus as plausible given the extreme 2026 European heatwaves, where France recorded its hottest day on 23 June with 44.3°C in Pissos and 44.0°C at Paris-Charles de Gaulle [4][5]. While July 12 has not yet occurred in 2026, the mid-30s forecast aligns with the post-heatwave cooling trend observed on 13 July, where maxima centered near 35–36°C [2]. The 0% probability likely misrepresents the market’s actual positioning, which heavily favours the 35°C bracket.

Traders must monitor Météo-France’s daily synoptic bulletins and the 48-hour forecast updates for the Paris region, as shifts in wind direction from the Atlantic could suppress temperatures below the 35°C threshold. Recent coverage of the June heatwave highlights how rapid atmospheric changes can alter peak readings within hours [5]. Automated strategies should integrate real-time API pulls from AccuWeather’s July 2026 monthly forecast, which projects daily highs between 23°C and 39°C, to adjust conditional orders before settlement [3].

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

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 Polymarket Review UK. 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.

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.