Highest temperature in Paris on July 5?

Platform comparison

Market context

Paris is bracing for a scorching heatwave on 5 July 2026, with current forecasts pushing afternoon highs toward 36–37°C at Paris-Le Bourget, far exceeding the 0% crowd-implied probability for any specific temperature outcome. This market resolves to the exact degree bucket containing the day’s peak, meaning the current 0% YES price likely reflects a mispricing where traders have not yet accounted for the active heatwave building across northern France[5].

Historically, July highs in Paris average 26°C but frequently climb into the low 30s, with the monthly record hitting 43°C in 2019 during a severe heat event[4]. While temperatures rarely exceed 31°C in typical years[7], the current atmospheric pattern shows intense sunshine, very high UV levels, and warm overnight conditions limiting cooling relief, creating a high-probability scenario for a peak in the 29–31°C range[5]. The market’s thin volume and 48-hour forecast uncertainty mean pricing is highly sensitive to the next Météo-France or ECMWF update[2].

Traders should monitor real-time updates from Météo-France and ECMWF models, as the contract closes at 12:00 UTC on 5 July and is extremely sensitive to the final forecast revision[2]. A programmatically driven approach would ingest Wunderground’s historical daily data for LFPB and cross-reference it with live model outputs to identify deviations from the modal 29–31°C peak[2]. With the heatwave already delivering 36°C on 3 July and 37°C on 4 July, the dependency on the final 24-hour forecast update is the primary catalyst for price movement[5].

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

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.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Polymarket Bot UK 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.