Highest temperature in London on May 23?

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Market context

On 23 May 2026, the highest temperature recorded at London City Airport will fall into one of several defined ranges. The settlement will draw from Wunderground's historical weather data for that specific station, converting to Celsius. The 0% crowd probability suggests traders currently see no meaningful likelihood of an extreme high-temperature outcome, or the market may reflect early-stage liquidity constraints typical of long-dated weather contracts.

London's May temperatures historically cluster between 16–22°C, with outliers rare but documented. The Met Office records show that May highs exceeding 25°C occur roughly once per decade in the capital; readings above 28°C are exceptional. The current zero probability may reflect either a narrow range definition in the upper tiers or genuine consensus that typical spring conditions will prevail. Comparable May markets from prior years show that traders typically assign meaningful probability mass to ranges spanning 18–24°C, with tail outcomes receiving fractional allocations.

From a regulatory standpoint, this market operates under UK jurisdiction but faces cross-border considerations. The German GlüStV framework treats prediction markets as wagering products requiring specific licensing; US CFTC oversight applies if US persons access the platform, though weather derivatives fall outside direct CFTC jurisdiction if structured as binary options. Polymarket's standard KYC exemption—permitting trading up to $1,500 without full identity verification—applies here, lowering friction for retail participation in weather prediction. Traders should monitor Met Office seasonal forecasts released in April 2026 and any anomalous weather patterns in May itself, as these will drive late-market repricing.

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 PolyGram, 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?

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.

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 PolyGram?

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

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.