Highest temperature in London on May 27?

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Market context

On 27 May 2026, the highest temperature recorded at London City Airport will fall into one of several defined ranges. The market currently shows 0% probability across all temperature brackets, reflecting either thin liquidity or a genuine absence of trading activity at this early stage. Settlement hinges on Wunderground's historical weather data for that specific station, with the conditional token structure on Polygon allowing traders to hold positions across multiple outcomes simultaneously until the settlement window closes at midday on the resolution date itself.

London's late May temperatures typically cluster between 18°C and 22°C, though the city has recorded highs exceeding 25°C in roughly one year out of three during this period over the past two decades. The 2022 heatwave pushed May temperatures into the low 30s, an outlier event that reshaped expectations around late-spring extremes in south-east England. Historical volatility in this window—driven by Atlantic weather systems and occasional continental air masses—means the full range of plausible outcomes carries non-trivial probability, yet the market's current flat pricing suggests traders are either waiting for seasonal forecasts to sharpen or treating this as a low-priority contract.

The UK Met Office publishes its monthly outlook in early May, typically offering guidance on temperature anomalies for the final weeks of the month. Traders monitoring the European model runs in mid-May will gain clearer sight of high-pressure systems or frontal activity scheduled for late May. Any significant revision to seasonal forecasts—particularly signals of an unusually warm or cool spell—could trigger repricing across the temperature brackets, though the settlement date's proximity to the contract's launch window leaves limited time for major catalyst-driven moves.

Methodology

This page is a comparison snapshot: one live quote (Polymarket), four reference venues with their key attributes, and a single execution path — every trade button routes to Polymarket UK, which mirrors the Polymarket order book directly.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket UK, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket UK 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.

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.