Highest temperature in London on June 12?

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Market context

The settlement hinges on the single highest temperature reading at London City Airport on 12 June 2026, measured in Celsius and resolved against Wunderground's historical weather database. The crowd currently assigns zero probability to any outcome, suggesting either insufficient liquidity or genuine uncertainty about which temperature band will be hit.

London's June temperatures typically range between 18–24°C, with extremes occasionally reaching 28–30°C during warm spells. Historical data from the Met Office shows that temperatures above 25°C occur in roughly one-third of June days across the capital, whilst readings exceeding 30°C remain rare but not unprecedented—the UK experienced a 40.3°C maximum in July 2022, though London itself rarely climbs that high. The 0% implied probability reflects the market's nascent state rather than a genuine forecast that no temperature will be recorded; traders should treat this as a liquidity gap rather than genuine conviction.

The relevant catalyst is the Atlantic weather pattern developing through late May and early June 2026. Traders should monitor the European Centre for Medium-Range Weather Forecasts (ECMWF) and UK Met Office extended forecasts from mid-May onwards, which will clarify whether a high-pressure system or Atlantic low dominates the period. Recent seasonal outlooks suggest near-normal temperatures for early summer across the UK, though individual days can deviate sharply. The settlement window closes at midday on 12 June, so morning forecasts published that day will be the final information available before resolution.

Methodology

We track Highest temperature in London on June 12? on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

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?

Who Will Win is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Who Will Win triggers a quick verification flow that finishes in 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.