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 determine which range this market resolves to. The settlement window closes at 12:00 UTC that day, with Wunderground's historical data serving as the authoritative source. The 0% crowd probability suggests traders are either absent from this market or treating it as a placeholder pending liquidity entry.

London's May temperatures typically range between 15–22°C, though outliers occur. Historical records show that late May heat waves can push readings above 25°C, whilst cooler northwesterly flows occasionally suppress highs to 12–14°C. The 2022 May heatwave saw London reach 29.1°C on the 20th, demonstrating that late-spring extremes are meteorologically plausible rather than speculative edge cases. Seasonal normals and recent decade trends suggest mid-range outcomes (18–23°C) carry the highest frequency, which should anchor baseline expectations before any specific weather pattern emerges.

Traders should monitor the UK Met Office's extended forecast from mid-May onwards, as atmospheric patterns 10–14 days ahead begin stabilising. High-pressure systems tracking from the continent typically drive warmer outcomes, whilst Atlantic low-pressure systems favour cooler, wetter conditions. Funding rates and spot positioning on weather-derivative platforms like Weathernews or Windy may signal institutional positioning if significant capital moves into May temperature bets. Any notable El Niño or North Atlantic Oscillation shifts reported in April–May meteorological bulletins could shift probabilities materially, though such shifts remain inherently uncertain at a six-month horizon.

Methodology

This page reads Highest temperature in London on May 23? on-chain. Polymarket's quote comes directly from the Polygon order book — the only comparable venue with on-chain settlement. Kalshi (USD, off-chain), Betfair (GBP/EUR, off-chain) and Manifold (play-money) are listed for comparison. Every CTA routes to PolyGram, which mirrors the Polymarket order book directly.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

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.

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.

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.