Highest temperature in London on June 28?

Platform comparison

Market context

The underlying real-world event is the peak temperature recorded at London City Airport on 28 June 2026, a date that has already passed with the settlement window closing in 12 hours. Polymarket prices this contract today with a 0% implied probability for the "YES" outcome, reflecting the crowd’s certainty that the temperature will not hit the specific threshold required for a payout, despite the market’s $48.6K volume and the $29.5K concentrated on the 26°C outcome.

Historical context frames this near-zero probability against the backdrop of June 2026’s record-breaking heatwave, where London sweltered to 36.1°C on 24 June, the hottest June day on record for the southeast, peaking at 36°C in Wisley. Yet, the Met Office noted that 26.6°C at Kew Gardens was the hottest day of 2026 so far before the 24th, suggesting that while extreme heat is common, the specific threshold for this market may be set above recent local airport readings, which hovered around 25–26°C on 28 June.

Traders should monitor the final Wunderground data release for London City Airport, which is the sole resolution source, and watch for any amber heat warnings that could indicate delayed data publication or anomalies. The Met Office has issued an amber warning for heat into Saturday, and recent reports from The Telegraph highlight how thunderstorms and downpours after extreme temperatures have caused airport chaos, potentially affecting data integrity. With the settlement window ending at 12:00 UTC on 28 June, the on-chain mechanics on Polygon using USDC and conditional tokens will resolve based on this single data point, leaving no room for second chances.

Sources: 1 · 2 · 3 · 4 · 5

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 Kalshi UK, 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.

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.