Highest temperature in Paris on May 25?

Platform comparison

Active sub-markets

Market context

On 25 May 2026, the highest temperature recorded at Paris-Le Bourget Airport will settle this market into one of several temperature bands. The settlement relies on historical data from Weather Underground, which archives daily extremes from this official station located north-east of central Paris. The 0% crowd probability suggests either extreme confidence in a specific range or minimal trading activity; comparing this against competing platforms reveals material differences in how such niche weather markets are priced. Kalshi, which operates under CFTC oversight in the US, typically shows tighter spreads on weather contracts through institutional participation, whilst Polymarket's Ethereum-based model attracts retail flow with lower barriers to entry but wider bid-ask gaps on low-volume pairs. Betfair's decimal odds format can obscure true implied probabilities for casual traders unfamiliar with the conversion, whereas Smarkets' fractional display offers clearer visual comparison across ranges.

Historical May temperatures at Le Bourget cluster between 15°C and 25°C, with occasional spikes above 28°C during heat waves. The 2022 European heat event saw Paris reach 30°C in late May, establishing a recent precedent for elevated readings. Traders should monitor European weather forecasting updates from Météo-France and the European Centre for Medium-Range Weather Forecasts (ECMWF) in the fortnight preceding settlement. Spring 2026 Atlantic oscillation patterns and any developing high-pressure systems over continental Europe will be the primary catalysts affecting temperature trajectories. The settlement window closes at noon UTC on the day itself, creating a hard deadline for final price discovery that differs from Betfair's evening settlement conventions on similar markets.

Methodology

We read Highest temperature in Paris on May 25? 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

Settlement is the biggest difference between the four platforms: Polymarket on-chain in USDC (instant), Kalshi USD via CFTC (T+1), Betfair and Smarkets in local currency via bank withdrawal (T+1 to T+3). PolyGram routes every trade directly into Polymarket's on-chain settlement, which is why payouts land fastest.

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.

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.

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.