Highest temperature in Paris on July 20?

Platform comparison

Market context

Paris-Le Bourget is about to record its highest temperature for 20 July 2026, with forecasters warning of an intense heatwave pushing readings between 36°C and 39°C, potentially touching 40°C [4][5]. Despite this, the Polymarket contract for “Highest temperature in Paris on July 20?” currently prices the 24°C outcome at 100%, while the crowd-implied probability for any higher range sits at 0% [1]. This stark divergence between live weather forecasts and on-chain pricing suggests the market is misaligned with current atmospheric conditions, likely due to lagging sentiment or a lack of liquidity in the conditional tokens settled in USDC on Polygon.

Historically, July in Paris averages highs of 25–27°C, but canicules frequently drive temperatures to 35–40°C for multiple days, especially in mid-July [2]. The 4 July 2026 event saw a peak of 31°C at the same station, which traders previously priced as practically excluded from the highest range, mirroring today’s 0% sentiment for elevated outcomes [3]. However, Météo-France now indicates this heatwave will persist beyond 14 July with no clear end, increasing the likelihood that 20 July will exceed the 24°C frontrunner [5].

Traders should monitor daily updates from Météo-France and Wunderground, the official resolution source, as cooler Atlantic air is forecast to arrive only by the end of the week, potentially dropping temperatures below 30°C [4]. Any delay in this relief could sustain the 36–40°C range, directly challenging the current market consensus. With settlement closing at 12:00 UTC on 20 July, the dependency on real-time temperature logs means the 0% probability may shift rapidly if the heatwave holds.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Paris on July 20? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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

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 PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.