Highest temperature in Paris on July 22?

Platform comparison

Market context

Paris-Le Bourget Airport is the reference point, and the contract settles on the day’s highest observed temperature there by 12:00 UTC, so Polymarket’s 0% yes price implies the market is currently assigning no meaningful chance to an outcome that has not yet been observed. In practice, that sort of pricing usually reflects either a stale book, very thin liquidity, or the fact that traders expect the resolution window to close before the day’s warmest part has fully developed.

For context, Paris summer highs can move quickly with cloud cover, wind direction and timing of frontal passages, and airport stations often run a touch cooler than dense-city readings. On a late-July day, the key issue is often whether the peak arrives in the late morning or after midday; if the market’s settlement window ends at 12:00 UTC, later afternoon heating at the station will not count, which can matter more than the headline daily forecast.

A trader watching this contract would focus on the morning forecast updates for northern Île-de-France, any shifts in cloud and rainfall timing, and whether the station’s highest temperature is likely to be reached before noon UTC. On Polymarket, the trade is executed in USDC on Polygon through conditional tokens, so the price is a direct expression of what participants think the settlement source will record, not a general view of Paris weather.

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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

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 Polymarket Scam?. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.