Highest temperature in Madrid on July 31?

Platform comparison

Market context

Madrid’s outcome will be set by the day’s **highest reading at Adolfo Suárez Madrid-Barajas Airport Station**, not by the citywide forecast or the midday average, so a late-afternoon spike matters more than the morning temperature. Recent Madrid July climatology still points to hot conditions: typical highs cluster around the low-to-mid 30s °C, and AccuWeather’s Madrid monthly pages show late-July highs in the 30s °C rather than anything close to cold weather[1][7]. Against that backdrop, the market’s current 0% YES crowd price looks like an extreme sceptical stance rather than a claim that heat is impossible, especially given that Madrid-Barajas has already posted 35.9°C to 38.7°C readings in recent observations and forecasts[12][18].

For platform comparison, Polymarket typically prices this kind of event as an implied probability, while Kalshi and Betfair/Smarkets are more naturally read through decimal odds and net payout after fees, so the same weather view can look different after transaction costs and spread. On a day like this, the main watchpoint is whether the station forecast edges towards the high 30s °C or a brief hotter peak, because the settlement uses the *single highest* temperature recorded on the station’s Wunderground history page. A Spanish press forecast published earlier today pointed to a Madrid maximum of 38°C and minimum of 22°C, which is consistent with a non-zero chance of the upper end being tested[4]. KYC and access also differ across books: exchange-style venues can be more restrictive by jurisdiction, while prediction-market access and fee treatment can materially affect a thin weather contract’s effective price.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest temperature in Madrid on July 31? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. The live probability is the Polymarket mid; the comparison columns summarise each venue's fee structure, KYC, settlement currency and payment rails. Every CTA routes to Robinhood Prediction Markets, 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

Polymarket vs Kalshi — which is better?

Depends on your location. Kalshi is CFTC-regulated, US-only with full KYC. Polymarket is global, on-chain, no KYC up to $1,500. Polymarket has ~10x higher liquidity but higher regulatory risk.

Which platform has the deepest liquidity?

Polymarket — by a wide margin. Top markets reach $50-500M volume, Kalshi ~$200M cumulative, Betfair similar. Deeper liquidity means your trade moves the quote less.

Is Betfair a Polymarket alternative?

Only partially. Betfair Exchange is UK-focused with a sports-betting emphasis; they have politics markets but with thinner liquidity than Polymarket. Settlement in GBP/EUR, 2-5% commission on winnings.

What about Smarkets as an alternative?

Smarkets is a UK betting exchange with a lower default commission (2%) than Betfair. Liquidity on political markets is below Polymarket, comparable to Kalshi. Geo-blocked in many jurisdictions.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Robinhood Prediction Markets offers a fiat on-ramp via Klarna or SOFORT (DE/AT/CH) and converts internally to USDC for the Polymarket order book. T+1 processing.