Highest temperature in Paris on July 20?

Platform comparison

Market context

Paris will face its peak summer heat on 20 July 2026, with the highest temperature recorded at Paris-Le Bourget Airport determining the outcome of this weather market. The crowd currently assigns a 0% implied probability to the YES outcome, suggesting consensus that the temperature will fall outside the specific range offered, likely because traders expect conditions to remain below the threshold or for the range to be misaligned with historical July peaks.

Historically, July in Paris has seen extreme heat, with the city recording 42.6°C in July 2019 and 40.1°C in July 2022, both at the same Le Bourget station used for resolution [1]. These comparable cases indicate that while 0% probability implies certainty of a lower outcome, the region’s climate history shows frequent breaches of 35°C, making the current pricing potentially vulnerable if forecast models shift toward a heatwave. Traders should view the 0% line as an underdog position that offers value if long-range models begin projecting high-pressure systems over western Europe.

Key catalysts include the release of the European Centre for Medium-Range Weather Forecasts (ECMWF) seasonal outlooks and any announcements from Météo-France regarding upcoming heat alerts, which could reshape temperature expectations weeks before settlement [2]. With the settlement window ending on 2026-07-20T12:00:00Z, traders must monitor daily 10-day forecast updates, as a sudden shift in atmospheric pressure patterns could invalidate the current consensus and expose the 0% probability as a contrarian value spot.

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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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 Who Will Win 2026. 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'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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 2026 trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.