Highest temperature in Paris on August 20?

Platform comparison

Market context

On 20 August 2026, the highest temperature recorded at Paris-Le Bourget Airport will fall within one of several defined ranges, measured in degrees Celsius. The market currently prices all outcomes at 0% on Polymarket's USDC/Polygon infrastructure, indicating either a technical settlement issue or genuine uncertainty about which temperature bracket will resolve true. Traders holding conditional tokens for any range are effectively betting against a crowd that has not yet committed capital to this contract.

Historical August temperatures at Le Bourget show considerable variability. The station recorded 40.3°C on 25 August 2003 during Europe's severe heatwave, whilst more typical August highs cluster between 25–28°C. The 2022 European heat event saw Paris reach 39.5°C in mid-August, suggesting that extreme outcomes above 35°C remain plausible but infrequent. The 0% crowd probability likely reflects low trading volume rather than confidence that the event cannot occur; similar weather markets often show skewed probabilities until closer to settlement.

Traders should monitor European weather forecasting from mid-August 2026 onwards, particularly outputs from Météo-France and the European Centre for Medium-Range Weather Forecasts. Atmospheric blocking patterns, jet stream positioning, and any developing heat domes over western Europe in early-to-mid August will drive material repricing. The settlement window closes at 12:00 UTC on 20 August, so final forecasts from 18–19 August will carry the most weight. Resolution depends entirely on the Daily Observations table at Weather Underground for Le Bourget, not summary figures, making data source verification critical for dispute avoidance.

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

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%.