Highest temperature in Madrid on June 28?

Platform comparison

Market context

On 28 June 2026, the Adolfo Suárez Madrid-Barajas Airport will record its peak temperature, a real-world event that determines the outcome of this prediction market. The crowd-implied probability for the highest temperature falling into the upper range is currently 0% YES, suggesting consensus believes extreme heat is unlikely. Historically, Madrid’s June daytime maximums average 28°C with low humidity, though record-breaking heatwaves have occurred. Notably, on 28 June 2019, the airport hit 40.7°C, the highest June temperature recorded there between 1920 and 2026, while recent weeks in 2026 saw Cantabria reach 43.7°C and Andujar 45.1°C, indicating a volatile, warming climate pattern across Spain.

Traders should monitor the European heatwave trajectory and official meteorological announcements for the Iberian Peninsula, as these are the primary catalysts for temperature spikes. The current consensus heavily favours moderate temperatures, but value may sit contrarianly on the upper range if the 2026 heatwave persists into late June, given the unprecedented regional records already logged. With settlement ending at 12:00 UTC on 28 June, dependencies include real-time Wunderground data updates and any sudden shifts in atmospheric pressure systems. The 0% implied probability appears overly cautious against the backdrop of Spain’s highest June average since 1950, offering a potential underdog angle for those betting on a repeat of the 2019 extreme.

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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

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Who Will Win 2026. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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.

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.