Highest temperature in London on July 20?

Platform comparison

Market context

London City Airport recorded its peak temperature for 20 July 2026 at 25°C, a figure that now locks the outcome for traders holding conditional tokens on the Polygon network. The market, priced in USDC, has settled with the 25°C option at 100% probability, rendering the 0% YES price for lower ranges irrelevant as the event has passed. On-chain mechanics confirm the resolution source as Wunderground’s historical daily data for EGLC, which aligns with the frontrunner outcome now dominating the order book.

Historical July peaks at this station typically hover between 22°C and 28°C, with 25°C representing a median high rather than an extreme outlier. In recent years, similar mid-July days have seen temperatures cluster around this mark, making the current 100% assignment to 25°C consistent with long-term climatic patterns rather than a speculative anomaly. Traders reviewing past settlement data will note that deviations beyond ±2°C are rare, reinforcing the market’s confidence in this specific range.

No further catalysts remain to watch, as the settlement window closed at 2026-07-20T12:00:00Z and the official data is already published. The only dependency was the Wunderground update for EGLC, which has been confirmed and incorporated into the resolution logic. With the outcome fixed, liquidity will migrate to new contracts, and USDC positions tied to this market will reflect the final payout based on the 25°C result.

Sources: 1 · 2

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 PolyGram, which mirrors the Polymarket order book directly.

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

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.

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 PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.