Highest temperature in London on June 25?

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Market context

London is currently bracing for a significant heat spike, with temperatures at Heathrow soaring to 37.8°C yesterday, marking the hottest day of the year so far and shifting the immediate outlook from mild to extreme [10]. This rapid escalation in the last 24 hours has driven the crowd-implied probability for the highest temperature at London City Airport to exceed the 2% threshold, as the region transitions into its warmest seasonal window starting mid-June [1][3]. The current 2% YES probability reflects a market that is still cautious despite the recent record, but the historical context suggests June 25 is a plausible date for peak temperatures, given that the warm season lasts nearly three months with average daily highs above 20°C [1].

Traders must monitor the Met Office forecast updates for Thursday, which currently predicts a high of 31°C at London City Airport, alongside any sudden shifts in southerly wind patterns that could push temperatures higher [3][7]. The primary catalyst is the continuation of the heat dome that caused the 37.8°C record at Heathrow, as similar atmospheric conditions often affect the entire city, though local airport readings can vary slightly due to urban cooling effects [10]. Watch for the next 12-hour pressure trend, which is currently falling, as a drop in pressure often correlates with rising temperatures in this specific weather pattern [3]. If the heat dome persists without a break in cloud cover, the probability of exceeding the current temperature range could rise sharply before the settlement window closes.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in London on June 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 Prediction Today — 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

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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.

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