Highest temperature in Paris on July 4?

Platform comparison

Market context

Paris is bracing for a powerful heatwave pushing temperatures sharply higher across northern France on 4 July 2026, with forecasts indicating midday highs near 37°C at the Paris-Le Bourget Airport Station. This real-world intensity frames the current market pricing on Polymarket, where the contract for "31°C" sits at 43% probability, while the "30°C" outcome on the adjacent 5 July market trades at 52%. The crowd-implied 0% probability for a "YES" on the lower temperature bands reflects the on-chain consensus that the heat will be severe, driven by conditional tokens settled in USDC on the Polygon network.

Historical precedents from the 2026 European heatwaves, where France recorded its hottest day ever at 44.3°C in Landes on 23 June, suggest that Paris is unlikely to experience a cool anomaly during this period. Recent guidance from meteorological models aligns the median expectation with 31°C, as traders discount the risk of residual warmth if subsidence strengthens while assigning slim odds to cooler outcomes like 29°C which would require faster advection of maritime air. The balmy overnight lows hovering around 21°C further limit cooling relief, reinforcing the likelihood of sustained high temperatures.

Traders should monitor the official Wunderground resolution data for the Paris-Le Bourget station as the primary catalyst, alongside any updates from Météo-France regarding the persistence of the heatwave. The settlement window ending 12:00 UTC on 4 July creates a tight dependency on the first published data point for that date, after which revisions to recorded temperatures will no longer be considered. Recent news coverage of the brutal heat wave affecting western Europe, including red heat warnings in the UK, underscores the regional scale of this event and the high probability of temperatures exceeding seasonal averages.

Sources: 1 · 2 · 3 · 4 · 5

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.