Highest temperature in London on June 25?

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Active sub-markets

Market context

The real-world event this market tracks is the peak air temperature recorded at London City Airport on 25 June 2026, measured in degrees Celsius and sourced from Wunderground. Historical data shows London City Airport regularly experiences daily highs above 25°C during late June, with the warm season running from mid-June to early September and average highs exceeding 19°C [3]. Recent reports indicate London is forecast to reach 30°C by the upcoming bank holiday, suggesting June 25 could be among the year’s hottest days so far [9]. A comparable case occurred on 23 June 2026, when NW3 Weather recorded a maximum of 33.9°C at the same location, demonstrating that temperatures well above 30°C are meteorologically plausible in this period [8].

Traders should monitor official Met Office forecasts and BBC Weather updates for any sudden shifts in cloud cover or wind patterns that could suppress peak temperatures [5][1]. The primary catalyst is the timing of the daily high, which typically occurs between 13:00 and 16:00 BST; any rain or strong westerly winds before this window could lower the maximum [1]. Recent news from the BBC highlights that London may be heading for its warmest day of the year, reinforcing the likelihood of high temperatures on 25 June [9]. The current 0% YES probability appears inconsistent with these historical and forecast trends, suggesting a potential mispricing in the market.

Regulatory accessibility hinges on jurisdiction-specific rules: German GlüStV implications may restrict participation for residents unless the platform complies with state licensing, while US CFTC reach could limit access for US traders if the market is deemed a futures contract. However, the “no-KYC up to $1,500” threshold means this market remains accessible to most users without identity verification, provided their stake stays below that limit. This structure enhances liquidity but does not override national legal barriers. Facts remain clear: the event is physically probable, the probability is likely mispriced, and accessibility depends on local compliance, not platform policy alone.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on June 25? on the five venues with material liquidity for prediction markets. Live odds come from the Polymarket Polygon order book — the only source that ships real-time data under an open licence. For Kalshi, Betfair and Manifold we list platform attributes (fee, KYC, settlement, payment) instead of fabricated odds, because their APIs use non-comparable contract definitions.

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

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.

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.