Highest temperature in London on July 3?

Platform comparison

Market context

The highest temperature recorded at London City Airport on 3 July 2026 is the real-world event this contract resolves to, measured in degrees Celsius. Polymarket prices this conditional token today with the 27°C outcome commanding a 97% share of the USDC liquidity on the Polygon network, while the 28°C outcome sits at just 2%. The market currently assigns a 0% probability to any temperature falling outside the 26–29°C range, reflecting a tight consensus among traders holding these on-chain positions.

Historical data frames this near-certainty, as July is London’s hottest month with an average high of 72°F (22°C) at London City Airport, yet recent years have seen peaks near 26–27°C. The absolute record for London remains 40.2°C from July 2022 at Heathrow, but the City Airport station typically records lower extremes due to its urban location and proximity to the Thames. Current readings from 4 July show a high of 26°C, suggesting the 3 July peak likely mirrored this, reinforcing the 27°C frontrunner status.

Traders should monitor the Met Office daily forecasts and Wunderground resolution data, as the settlement window closes only after the first data point for 3 July is published. No specific weather announcements are pending, but the dependency on the official resolution source means any delay in data publication could impact liquidity timing. The 24°C maximum feels-like temperature forecast from the Met Office for the period indicates stable conditions, with no extreme heat warnings issued that would challenge the 27°C consensus.

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Methodology

This page reviews Highest temperature in London on July 3? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Kalshi UK, which mirrors the Polymarket order book at 0% fees.

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.

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.