Highest temperature in Madrid on July 21?

Platform comparison

Market context

The settlement hinges on the single highest temperature recorded at Madrid-Barajas Airport on 21 July 2026, measured in Celsius and resolved via Weather Underground's historical data. The 0% crowd probability suggests either extreme confidence in a specific temperature band or minimal trading activity, making this a sparse market with limited price discovery.

Madrid's July climate is reliably hot, with average highs around 32–33°C and historical peaks frequently exceeding 36°C. The city has experienced temperatures above 40°C during heat waves, most recently in summer 2022 when Spain endured sustained extreme heat. Barajas Airport, situated on the city's outskirts, typically records slightly lower temperatures than central Madrid due to its elevation and distance from urban heat effects. Historical July data from the station shows a range between 28°C and 42°C depending on synoptic conditions, providing a broad reference frame for where the true probability mass should sit.

The key variable is whether an Atlantic high-pressure system or African heat dome dominates European weather patterns in mid-July 2026. Spain's meteorological service and European weather models will become increasingly reliable from early July onwards. Recent summers have shown a tendency towards prolonged heat events rather than isolated hot days, though single-day extremes remain contingent on specific atmospheric configurations. Traders should monitor seasonal forecasts from ECMWF and national weather agencies as the settlement date approaches, particularly any signals of blocking patterns that could drive anomalous heat into the Iberian Peninsula.

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Who Will Win 2026, which mirrors the Polymarket order book directly.

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'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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 2026 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.