Highest temperature in Paris on August 21?

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Market context

Paris-Le Bourget Airport will record its highest temperature on 21 August 2026, with the market resolving to whichever temperature band captures that daily maximum as logged in Weather Underground's Daily Observations table. The current crowd-implied probability of 1% YES reflects either an extremely narrow temperature range or a misalignment between trader expectations and the actual resolution bands available.

August temperatures at Le Bourget historically peak between 24–27 °C, with extremes reaching 28–30 °C during heat waves. The 1% pricing suggests the market is pricing in either a very high threshold or a specific narrow band that sits well above typical late-summer conditions. Comparable European airport stations show August highs clustering in the mid-to-high 20s Celsius; only sustained heat dome events push readings materially higher. The low probability may indicate traders expect a cooler-than-average August or that the resolution band itself is set at an outlier threshold.

Traders should monitor European seasonal forecasts and Atlantic pressure patterns from June onwards, as these drive August weather across northern France. The Météo-France outlook and European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble runs will be critical inputs. Any signals of a summer heat wave building over continental Europe in late July could shift implied probabilities sharply. Settlement occurs at 12:00 UTC on 21 August 2026, giving traders a fixed window to observe the actual Le Bourget reading before resolution locks in on Wunderground's Daily Observations table.

Methodology

This page reads Highest temperature in Paris on August 21? on-chain. Polymarket's quote comes directly from the Polygon order book — the only comparable venue with on-chain settlement. Kalshi (USD, off-chain), Betfair (GBP/EUR, off-chain) and Manifold (play-money) are listed alongside for venue context. Every CTA routes to BTC Prediction, which mirrors the Polymarket order book directly.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

UK Frequently Asked Questions

Why USDC and not ETH or USDT?

USDC is the Polygon standard — audited reserves (Circle, monthly attestation), deepest order book, low gas costs. ETH volatility would distort probability quotes; USDT has thinner Polygon liquidity than USDC.

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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.

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