Highest temperature in Paris on August 18?

Platform comparison

Market context

On 18 August 2026, the highest temperature recorded at Paris-Le Bourget Airport will determine which range this contract settles into. Polymarket currently prices YES at 0%, reflecting either extreme confidence in a specific temperature ceiling or minimal trading activity on this particular outcome band. The settlement hinges on Weather Underground's Daily Observations table rather than summary figures, a distinction that matters when intraday peaks diverge from official highs—a common occurrence at major airport stations where measurement timing and sensor placement influence recorded values.

August temperatures at Le Bourget historically cluster between 20–28°C, with extremes reaching into the low 30s during heat waves. The 2003 European heat event saw Paris peak near 40°C, whilst more recent summers have produced occasional days exceeding 30°C. The current 0% probability suggests traders are either heavily concentrated in a single range or the market lacks sufficient liquidity to price uncertainty across multiple bands. Historical volatility in late-summer Parisian weather—influenced by Atlantic systems, continental air masses, and occasional Mediterranean incursions—typically creates meaningful spreads between daily highs and lows of 8–12°C.

Météo-France's seasonal forecasts and any issued heat alerts between now and August 2026 will signal whether conditions favour above-average temperatures. Real-time catalysts include the North Atlantic Oscillation phase, which influences European summer patterns, and any exceptional heat dome development in late July or early August. Traders monitoring this contract should track European weather model consensus runs from mid-August onwards, as these provide the most reliable 10–14 day guidance for specific airport observations.

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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

UK Frequently Asked Questions

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.

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%.