Highest temperature in Paris on July 4?

Platform comparison

Market context

Paris is bracing for a powerful heatwave that will push temperatures sharply higher across northern France on 4 July 2026, with the Paris-Le Bourget Airport Station expected to record highs near 37°C. This real-world event frames the current crowd-implied probability of 0% for the "YES" outcome on Polymarket, where the contract is priced today as virtually certain to resolve in the lower temperature range. The on-chain mechanics, settled in USDC on Polygon via conditional tokens, reflect a market that has already discounted the possibility of extreme heat exceeding the threshold, despite the scorching conditions forecast.

Historical precedents show that France has recorded temperatures as high as 44.3°C during the European heatwave of June 2026, yet Paris itself typically caps around 40°C even in historic spikes, as seen in late June when peaks reached 37–40°C under blazing sun. The current forecast for 3–4 July mirrors those intense conditions, with morning lows near 22–23°C and afternoon highs soaring to 36–37°C, suggesting the day will be one of the hottest of the summer so far but unlikely to breach the resolution threshold that would trigger a "YES".

Traders should monitor the official Wunderground data release for the Paris-Le Bourget station, which will confirm the highest temperature recorded at any time on 4 July, and watch for any sudden shifts in the heatwave intensity announced by Météo-France. Recent reports from Sortiraparis and Euronews confirm that the heatwave has been historic, with 18 fatalities across France, but the cooling trend expected later in June did not fully materialise, leaving conditions nearly identical to the previous day. No further announcements are scheduled, so the dependency remains solely on the real-time temperature data from the station.

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Methodology

We track Highest temperature in Paris on July 4? 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

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 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 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.

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.