Highest temperature in London on June 25?

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Market context

The real-world event driving this market is the peak temperature recorded at London City Airport on 25 June 2026, with the crowd currently assigning only a 1% chance that the temperature will exceed the highest range threshold. Historical data frames this low probability sharply: London’s June record stands at 35.6°C, set in Southampton in 1976, and while recent heatwaves have pushed Heathrow to 34.2°C, sustained temperatures above 37°C in central London remain exceptionally rare [2]. The Met Office has forecast highs near 37°C for this week, yet such extremes typically occur in short bursts rather than as all-day averages, making a breach of the top range a statistical outlier rather than a likely outcome [1].

Traders should monitor the UK Health Security Agency’s red heat-alert extensions and the Met Office’s hourly updates, as these dictate whether the forecasted 37°C peak materialises or dissipates [2]. A recent red alert extension for London by 24 hours signals heightened risk, but dependencies on wind patterns and cloud cover could suppress temperatures below the critical threshold [2]. The settlement source, Wunderground, will capture the single highest reading for the day, meaning even a brief spike could resolve the market, yet current dependencies suggest such spikes are unlikely to persist through the full settlement window [3].

For accessibility, German GlüStV regulations and US CFTC reach create a complex compliance landscape, though the “no-KYC up to $1,500” threshold allows most traders to access this market without identity verification, provided they stay within the limit. This specific market’s low probability and narrow settlement window make it a high-risk, low-yield instrument, where the regulatory framework permits participation but does not guarantee favourable outcomes. Facts remain clear: the event is rare, the probability is minimal, and the regulatory environment permits access without KYC for smaller stakes.

Sources: 1 · 2 · 3 · 4 · 5

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 Polymarket Tax UK, 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?

Polymarket Tax UK 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 Polymarket Tax UK?

Zero. Polymarket Tax UK 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, Polymarket Tax UK triggers a quick verification flow that finishes in minutes.