Highest temperature in London on May 26?

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Market context

On 26 May 2026, the highest temperature recorded at London City Airport will settle this market into one of several Celsius bands. The settlement mechanism relies on Wunderground's historical weather data for that specific station, with the contract resolving once the day's peak temperature is finalised. Currently, Polymarket prices this contract with 0% implied probability across all temperature ranges, suggesting either a data lag in crowd pricing or extreme uncertainty about which band will ultimately contain the actual reading.

London's May temperatures have historically clustered between 18–24°C, with occasional peaks reaching 26–28°C during warmer years. The 2022 heatwave pushed late-May readings toward 30°C in parts of the capital, though City Airport's riverside location and urban heat-island effects create a microclimate distinct from broader London readings. Examining past May 26 data specifically shows considerable variance: some years have seen highs around 16°C during cooler springs, whilst others have reached into the mid-20s. This historical spread explains why traders cannot simply anchor to a single expected outcome.

The UK Met Office publishes extended forecasts roughly ten days ahead, with increasing reliability as May 2026 approaches. Atmospheric patterns in late spring depend heavily on whether Atlantic low-pressure systems dominate or high-pressure ridges establish themselves over the British Isles. Traders should monitor seasonal outlooks from the Met Office and European weather models in the weeks before settlement, as these will clarify whether May 2026 tracks toward cooler or warmer conditions. The settlement window closes at 12:00 UTC on the day itself, leaving traders minimal time to adjust positions once morning forecasts confirm the likely range.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

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?

PolyGram 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, PolyGram 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.