Highest temperature in Paris on May 25?

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Active sub-markets

Market context

On 25 May 2026, the highest temperature recorded at Paris-Le Bourget Airport will fall into one of several defined ranges. The settlement hinges on data from Wunderground's historical weather records for that specific station, with the settlement window closing at midday UTC. This is a straightforward meteorological outcome with no discretionary elements—the thermometer reading either falls within a given bracket or it does not.

Paris's late May temperatures typically cluster between 18°C and 24°C, though extremes have occurred. Historical data from the past decade shows May 25th highs ranging from 15°C to 28°C depending on the year, with most occurrences in the 20–24°C band. The 0% implied probability across the market suggests either extreme confidence in a specific outcome or insufficient liquidity across all ranges. On Polymarket, this would display as decimal odds; Kalshi and Betfair present the same underlying probabilities differently, with Kalshi's binary structure sometimes creating wider spreads on niche weather markets. Smarkets' commission-based model can affect effective odds on low-volume weather contracts differently than Polymarket's maker-taker fees.

Traders should monitor European weather forecasts from mid-May onward, particularly jet-stream positioning and high-pressure systems over France. The UK Met Office and Météo-France typically issue reliable 10-day outlooks by mid-May. Any unusual atmospheric patterns—Atlantic blocking highs or early heat waves—would shift probability distributions materially. Le Bourget's urban location near Paris means readings may run 1–2°C warmer than surrounding rural areas, a factor worth noting when comparing historical records from other French stations.

Methodology

This page compares Highest temperature in Paris on May 25? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. Live odds come from the Polymarket order book; the other venues' contract details are maintained manually because their APIs aren't directly comparable. Every CTA routes to PolyGram, which mirrors the Polymarket order book at 0% fees.

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.

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 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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, PolyGram triggers a quick verification flow that finishes in minutes.