Highest temperature in Paris on August 9?

Platform comparison

Market context

Polymarket currently has this Paris maximum-temperature contract priced around **1% YES**, which means traders on Polygon are assigning only a very small chance that the chosen Weather Underground outcome bucket will be hit for Paris-Le Bourget Airport before the settlement window closes. The payoff still runs through the usual Polymarket mechanics: USDC collateral, conditional tokens, and redemption only if the Daily Observations table on Weather Underground records a temperature that falls into the winning range.

For context, this market is being read against a hot August pattern rather than a cool one. Paris is forecast by several weather services to sit in the upper 20s to low 30s Celsius on 9 August, with some forecasts showing around 30°C or slightly above and others higher still, while recent regional commentary has described early-August heat returning to Île-de-France.[1][8][12] That helps explain why a 1% price looks like a tail outcome rather than a neutral one: the market is implying that an unusually low or otherwise non-standard recorded high is still highly unlikely, even with summer weather variance.[3][13]

A trader watching this should focus on the actual station observation, not the summary high/low figure, because the market rules make the Daily Observations table decisive if there is any discrepancy. The key catalysts are the final hourly sequence before the noon UTC settlement cut-off, any late-day cooling from showers or cloud cover, and whether Weather Underground updates the Paris-Le Bourget station data cleanly before the following day’s first datapoint appears.[3][12] In practical Polymarket terms, the contract only resolves once the temperature bucket is locked in, so any late change to the observed maximum can move a small-position market very quickly.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Paris on August 9? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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

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.

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%.