Highest temperature in Madrid on July 21?

Platform comparison

Market context

Madrid's peak temperature on 21 July 2026 will be measured at Adolfo Suárez Madrid-Barajas Airport, the official meteorological station for the city. The settlement window closes at midday UTC, capturing the full diurnal cycle for that date. Current crowd-implied probability stands at 0% YES, suggesting either extreme confidence in a specific temperature band or minimal trading activity on this particular contract variant.

Historical July data from Madrid-Barajas shows consistent patterns: average highs in the 32–35°C range, with extremes occasionally reaching 40°C during heat waves. The station's 30-year climate record indicates that temperatures exceeding 38°C occur roughly once every three to five years during mid-to-late July. The 0% reading across the board implies traders are either awaiting resolution data or the market structure itself lacks sufficient granularity to attract meaningful positions. Cross-platform comparison reveals no published sportsbook lines for weather-specific outcomes of this type, leaving prediction markets as the sole pricing mechanism.

Traders should monitor European weather forecasting updates from mid-July 2026, particularly anomaly alerts from Météo-France and AEMET (Spain's national meteorological agency). Any Atlantic blocking pattern or Saharan dust intrusion in the fortnight preceding the date could materially shift temperature expectations. Wunderground's historical database remains the binding resolution source, with temperature readings typically finalised within hours of the settlement window closing. The absence of current liquidity suggests this contract may see late-stage activity once forecasts crystallise closer to the event date.

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

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 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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Best Prediction Markets UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.