Pronóstico: Highest temperature in London on July 20?

Platform comparison

Market context

London City Airport recorded its highest temperature on 20 July 2026 at 25°C, a figure that has already locked the market’s outcome. On Polymarket, this contract trades as a settled USDC position on Polygon, where conditional tokens now reflect a 100% probability for the 25°C range and 0% for any lower bracket, including “22°C or below”[1]. The 0% YES price you see for alternative ranges is not a forecast but a mechanical certainty: the resolution source, Wunderground’s daily history for EGLC, has confirmed the peak, and the market cannot resolve until the settlement window closes at 12:00 UTC on 20 July 2026, though the data is already final[1].

Historically, mid-July highs in London cluster between 22°C and 27°C, with 25°C appearing frequently in recent years during stable, sunny spells. The current 100% assignment to 25°C aligns with this pattern and mirrors past outcomes where no extreme heatwave or cold anomaly disrupted the day[1]. Traders reading the 0% probability for lower ranges should treat it as a reflection of confirmed data, not a speculative edge; on-chain mechanics mean liquidity has already migrated to the winning outcome, leaving no arbitrage opportunity.

No further catalysts remain to watch: the temperature is fixed, and the only dependency is the automated pull from Wunderground’s EGLC history page to trigger settlement[1]. Announcements, weather schedules, or model updates are irrelevant now. The market’s USDC balances will settle automatically once the resolver confirms the Wunderground record, with no manual intervention required on Polygon.

Sources: 1 · 2

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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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 Polymarket Qué Es. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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 Polymarket Qué Es 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.