Highest temperature in London on May 25?

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Market context

On 25 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 and date, with the resolution window closing at midday. The 0% crowd probability suggests traders currently see little conviction in any particular temperature band, or the market may reflect early-stage liquidity constraints typical of weather derivatives with extended settlement horizons.

London's May temperatures have historically clustered between 16–22°C, with occasional outliers reaching 25°C or higher during anomalous warm spells. The May 2022 heatwave saw temperatures exceed 28°C across parts of the south-east, though City Airport—situated on the Thames estuary—typically records slightly cooler readings than central London owing to maritime influence. Comparable May forecasts from the UK Met Office and historical Wunderground archives show that extreme heat (above 26°C) occurs in roughly one year per decade during this month, whilst sub-15°C days remain plausible given variable Atlantic weather patterns.

Traders should monitor the UK Met Office's extended outlook and any Atlantic blocking patterns emerging in late April 2026, as these drive May weather trajectories. Regulatory accessibility for this market depends on jurisdiction: German traders face GlüStV compliance requirements for prediction market participation; US-based traders remain subject to CFTC oversight of derivatives, though no-KYC access up to $1,500 notional exposure typically permits small-stake weather bets without full identity verification. Settlement accuracy hinges entirely on Wunderground's station data integrity and timestamp recording protocols.

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

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.

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 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.