Highest temperature in Paris on July 24?

Platform comparison

Market context

Paris will experience some temperature on 24 July 2026, and this market resolves to whichever range bracket captures the highest reading recorded at Le Bourget Airport that day. The settlement mechanism pulls directly from Weather Underground's historical data feed for the station (LFPB), with a 12:00 UTC cutoff. Traders need to verify the Celsius toggle in Weather Underground's interface settings—the platform defaults to Fahrenheit in some regions, and misreading the scale would invalidate position logic.

July temperatures at Le Bourget typically peak between 24–27°C, though heat waves push readings into the low 30s. The 2003 European heat event saw Paris reach 40.3°C in August; more recently, July 2022 recorded 32.4°C at Le Bourget. The 0% crowd probability suggests either the market has insufficient liquidity or traders are pricing in a technical resolution risk rather than genuine uncertainty about whether a temperature will occur. Historical volatility and the broad range of plausible outcomes (15–35°C) make this a calibration exercise for algorithmic traders building weather-derivative models.

Monitoring Météo-France's seasonal forecasts and European medium-range weather models (ECMWF) becomes relevant from mid-July onwards. Any Atlantic blocking pattern or heat dome trajectory would shift implied probabilities weeks in advance. Programmatic approaches would benefit from conditional order logic tied to forecast updates rather than static entry points, since July weather in northern France remains genuinely uncertain until the final week.

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 Polymarket Bot 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.