Highest temperature in Paris on August 15?

Platform comparison

Market context

The Paris-Le Bourget Airport weather station will record its highest temperature on 15 August 2026, and Polymarket traders are pricing the likelihood of an extreme heat event at just 1% across all temperature brackets combined. This settlement hinges on Weather Underground's Daily Observations table rather than summary figures, a distinction that matters when automated systems report conflicting readings. The contract resolves in USDC on Polygon, with conditional tokens reflecting discrete temperature ranges that traders can exit independently before the 12:00 UTC close on the settlement date.

Historical August temperatures at Le Bourget show the station rarely exceeds 35°C on any single day, with the airport's all-time August high around 38–39°C across its operational record. The 1% crowd probability reflects baseline expectations that mid-August conditions will track within normal seasonal parameters for the Île-de-France region. Comparable European heat events—such as the 2022 summer anomaly that pushed Paris to 40°C—remain statistical outliers rather than typical August patterns, though climate trends have shifted baseline expectations upward over the past decade.

Traders monitoring this contract should track European weather forecasting updates from Météo-France and the European Centre for Medium-Range Weather Forecasts (ECMWF) as August approaches. Seasonal atmospheric patterns, including high-pressure systems over continental Europe and the Atlantic Oscillation index, will shape whether conditions favour above-normal or near-normal temperatures. Any significant heat advisory issued by French meteorological authorities in the week preceding 15 August would likely shift market pricing, as would real-time temperature readings during the morning and afternoon of settlement.

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.

UK Frequently Asked Questions

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Kalshi UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.