Highest temperature in Madrid on July 12?

Platform comparison

Market context

Madrid is currently experiencing the tail end of an intense summer heatwave that has pushed temperatures well above seasonal averages across central Spain, with the city recording highs of 42°C earlier in the week. This extreme thermal activity frames the current 0% crowd-implied probability for the “YES” outcome on the highest temperature bracket for July 12, as the market appears to have priced in a significant cooling trend or a shift to a lower temperature range despite the recent record-breaking conditions.

Historical precedents from the 2026 European heatwaves show that while Madrid frequently hits 40°C+ in July, the specific bracket in question likely sits above the observed 42°C peak from July 4–7, making the current zero probability a rational reflection of the day’s forecasted dip. AccuWeather’s July 2026 monthly outlook indicates daily highs typically range between 31°C and 39°C, suggesting that unless a sudden, unforecasted surge occurs, the temperature will likely resolve in a lower bracket than the one currently marked as impossible by traders.

Traders should monitor real-time updates from Wunderground for the Adolfo Suárez Madrid-Barajas Airport Station, as the settlement relies exclusively on this source’s recorded maximum for the day. While Euronews reported nine regions on alert for extreme heat earlier in July, the immediate catalyst is the hourly temperature progression on July 12 itself; any divergence between the live Wunderground reading and the crowd’s implied 0% probability would signal a potential mispricing, particularly if the heatwave persists unexpectedly into the weekend.

Sources: 1 · 2 · 3 · 4 · 5

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 Kalshi vs Polymarket. 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's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

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.