Highest temperature in Paris on May 22?

Platform comparison

Active sub-markets

Market context

The question is whether the Paris-Le Bourget Airport station reaches a given temperature band on 22 May, with settlement based on the day’s recorded high in Celsius. Paris is in a warm late-spring pattern, but not a reliably hot one: long-run May averages are around 20°C for highs, with typical daily highs generally in the high teens to low 20s, while occasional warm spells can push into the upper 20s or low 30s. That makes bands around 23°C to 26°C the most plausible in an average year, while very low outcomes usually need a notably cool, cloudy day. The crowd’s 0% YES implies this market is currently pricing no meaningful chance for the specific outcome being queried, which is unusually detached from the climatological baseline.

For comparison across venues, Polymarket displays crowd-implied probability directly, whereas Kalshi and Betfair/Smarkets are typically read through price or decimal odds, so the same temperature band can look different once fees and spread are included. On a live weather market, the main drivers are the afternoon forecast trend, cloud cover, and whether any frontal passage arrives over Île-de-France before the daily maximum is set, since the settlement source is the airport observation rather than a city-centre reading. Traders usually watch Met Office, Météo-France and airport forecasts through the morning, then compare them with Wunderground’s historical daily page once the station data are finalised. Fee and access differences also matter: Kalshi’s US access is more restricted, while Betfair and Smarkets can be affected by commission and local KYC, which can shift apparent pricing versus Polymarket’s order-book view.

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Methodology

We read Highest temperature in Paris on May 22? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live quote comes directly from the Polygon order book; the other three are listed with their platform attributes — fees, KYC, settlement currency, payment options — because a 1:1 contract comparison without API access would be guesswork.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Where can I trade this market with the lowest fees?

On PolyGram, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

PolyGram is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

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 does it cost to trade on PolyGram?

Zero. PolyGram routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.