Highest temperature in London on May 27?

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Market context

The settlement hinges on the single highest temperature reading at London City Airport weather station on 27 May 2026. The 0% crowd probability suggests traders are either confident the market will not resolve or are avoiding the uncertainty entirely. Late May in London typically sees daytime highs between 18–22°C, though the range of possible outcomes spans from single digits during unseasonal cold snaps to mid-20s during warm spells. The resolution mechanism depends on Wunderground's historical data feed for that specific station, which records hourly observations throughout the day.

Historical May temperatures at London City Airport show considerable variability. The station's records indicate that temperatures above 25°C occur roughly once every three to four years in late May, whilst readings below 10°C are rare but not unprecedented. The 2022 heatwave pushed late-May highs toward 28°C in parts of London, though City Airport sits closer to the Thames and experiences moderating maritime influence. The current zero probability likely reflects either thin liquidity or traders waiting for seasonal forecasts to crystallise closer to the settlement date.

The UK Met Office typically releases extended forecasts around two weeks before the target date, which will provide the first reliable signal for late-May weather patterns. Atlantic pressure systems and jet stream positioning in early May will determine whether continental warmth reaches south-east England or whether cooler maritime air dominates. Traders should monitor spring 2026 temperature trends and any emerging climate oscillations that might shift the probability distribution meaningfully away from the historical median.

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

Where can I trade this market with the lowest fees?

On Who Will Win, 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.

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.

What does it cost to trade on Who Will Win?

Zero. Who Will Win routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.