Highest temperature in London on May 25?

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Market context

The market seeks the highest temperature reading at London City Airport on 25 May 2026, with settlement determined by Wunderground historical data. The crowd currently assigns zero probability to any outcome, suggesting either extreme uncertainty about temperature ranges or a technical issue with market setup. May temperatures in London typically range from 15°C to 22°C, though the airport station—located on a peninsula in the Thames estuary—can record slightly different readings than central London due to its maritime exposure.

Historical May data from London City Airport shows that temperatures exceeding 25°C occur in roughly one year per decade, whilst readings above 28°C are exceptionally rare in this month. The 0% probability across all ranges is unusual and likely reflects the market's nascent state rather than genuine consensus that no temperature will be recorded. Comparable May days at the station have produced highs between 12°C and 26°C depending on whether Atlantic systems or continental air masses dominate. The lack of any distributed probability suggests traders should examine whether the market's range brackets are appropriately calibrated before committing capital.

The Met Office typically issues seasonal outlooks by April, which could inform expectations for late May weather patterns. Traders should monitor spring temperature trends through April and early May 2026, as persistent warmth earlier in the season sometimes correlates with above-average readings later. The settlement window closes at noon on 25 May, meaning the final temperature must be recorded before midday—a constraint that eliminates potential afternoon peaks on warmer days.

Methodology

This page reviews Highest temperature in London on May 25? 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.