Highest temperature in Paris on July 20?

Platform comparison

Market context

Paris is bracing for an intense heatwave in mid-July 2026, with forecasters warning temperatures could soar between 36°C and 39°C, potentially peaking at 40°C on some afternoons. This extreme heat is expected to persist for several consecutive days, placing significant strain on the city before cooler Atlantic air arrives later in the week. Such highs are historically rare for Paris, with the 40°C threshold reached only a handful of times in the city’s recorded history.

Historical data from previous French heatwaves, including the 2019 event when Paris hit 42.6°C, suggests that 20 July 2026 could fall within a similar high-temperature range. The current crowd-implied probability of 0% YES for any specific range appears to diverge sharply from meteorological forecasts, which indicate a strong likelihood of temperatures exceeding 35°C. Analysts reviewing Météo-France’s latest models note considerable uncertainty but confirm the heatwave could persist beyond 14 July, increasing the chance of record-breaking highs on the settlement date.

Traders should monitor daily updates from Météo-France and Wunderground, the official resolution source, for real-time temperature readings at Paris-Le Bourget Airport. Recent reporting from Le Monde confirms that no end to the heatwave is currently forecast, with conditions expected to remain severe until at least the following week. Key catalysts include the timing of the Atlantic cooling front and any official health advisories issued as temperatures climb, both of which could signal whether the 40°C peak is achievable before the settlement window closes.

Sources: 1 · 2

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

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.

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.

Do I need to KYC for this market?

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