Highest temperature in London on May 23?

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Active sub-markets

Market context

The settlement window closes on 23 May 2026 at noon, with the final temperature reading taken from the London City Airport weather station. This market resolves based on the highest temperature recorded across the entire calendar day at that specific location, converted to Celsius and grouped into the relevant range bracket.

London's May temperatures typically range between 15°C and 22°C, though the historical record for the month stands at 29.9°C, set in 2008. The 0% crowd probability suggests traders are pricing in either an unusually cool day or uncertainty about the exact range thresholds. May 23 specifically has seen highs of 18–20°C in most recent years, with only occasional excursions above 25°C. Comparable late-May weather patterns show that sustained warmth depends heavily on high-pressure systems tracking northward from continental Europe, an occurrence that occurs roughly once every three to five years during this period.

The key variable is the Atlantic weather pattern in the weeks leading to late May 2026. Traders should monitor extended-range forecasts from the Met Office and European weather models from mid-May onwards, as these typically gain reliability within the 10–14 day window. Any significant blocking high-pressure system over the continent would push warm air northward into the UK. The London City Airport station's urban location means it may record slightly elevated temperatures compared to rural sites, a factor worth considering when interpreting historical comparables.

Methodology

This page reviews Highest temperature in London on May 23? across five venues. We show live odds for Polymarket-based markets (sourced from the Polygon order book); for other venues we list platform attributes, since the comparable contracts are not exposed via a public API on every venue. Every CTA points at PolyGram — the application we operate, where you trade directly against the Polymarket order book at 0% fees.

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

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.

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 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.