Highest temperature in Paris on July 7?

Platform comparison

Market context

The real-world event driving this market is the peak summer heat expected across northern France on 7 July 2026, with forecasts predicting scorching temperatures that could reach 41°C at Paris-Le Bourget. In prediction markets, a YES share pays out if the highest temperature falls within the specific range you selected, while a NO share wins if it lands outside that range. Currently, the crowd implies a 0% chance for YES, suggesting most traders believe the temperature will not hit the upper threshold of the chosen range, despite the intense heatwave gripping the region.

Historical context frames this low probability against recent extremes; late June 2026 saw France record its hottest day ever, with temperatures hitting 40°C in Paris and a red alert issued for 54 departments [4][5]. However, Météo-France notes that odds of matching the severity of that late-June event remain low for this week, with highs expected near 36°C rather than the 41°C peak seen in some southern forecasts [2]. This distinction between the 36°C Paris expectation and the 41°C southern potential is crucial for reading the current 0% probability, as traders may be betting on the capital staying below the highest range limit.

Traders should monitor the evolution of the heat dome, which Météo-France describes as still uncertain, alongside daily updates from the weather agency [2]. Key catalysts include official red alert escalations and the timing of any potential storms later in the week, which could bring relief and lower temperatures [1]. While some forecasts suggest temperatures may drop slightly after 9 July, the immediate focus remains on whether the heat dome intensifies to push Paris closer to the 41°C mark seen in southern France [1][3]. No moralising is needed on whether to trade; the facts show a volatile weather situation where the 0% crowd probability may shift if the heat dome evolves unexpectedly.

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

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 Prediction Market UK. 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.

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.