Highest temperature in London on June 25?

Platform comparison

Active sub-markets

Market context

On 25 June 2026, London City Airport will record its peak temperature for the day, a single data point that determines the outcome of this prediction market. The current crowd-implied probability of 0% for a "YES" result suggests traders believe the temperature will fall outside the specific range being bet on, likely due to the extreme heat currently gripping the capital. Recent forecasts indicate temperatures could reach 40C in the coming days, with Wednesday and Thursday potentially hitting 40C and 39C respectively before a drop to 29C by Friday[1]. This volatility makes the 0% probability a stark reflection of the market’s confidence that the heatwave will push readings beyond the narrow range in question.

Historically, London has seen June temperatures spike dramatically, with records broken just days ago when the UK hit 34.8C in May, setting a precedent for unprecedented June heat[5]. Comparable cases like the 2018 heatwave, where temperatures soared above 38C, frame how to interpret the current 0% probability: it is not a dismissal of heat, but a calculation that the specific range is too low for the expected furnace conditions[1]. The cultural narrative of a "furnace" heatwave, reinforced by Red extreme heat warnings, suggests that traders are betting on the upper extremes of the temperature spectrum, leaving the lower range virtually unsupported[1].

Traders should monitor the Met Office’s daily updates for London City Airport, as sudden shifts in wind direction or cloud cover could alter the peak temperature[7]. The dependency on Wunderground’s official record means any discrepancy between forecast models and actual readings could trigger a rapid price correction. Recent news from the Standard highlights that the heat is expected to drop to 29C by Friday, making the timing of the 25th critical for the final resolution[1]. With the settlement window ending on 25 June 2026 at 12:00 UTC, the next 12 hours will be decisive in confirming whether the heatwave peaks as forecasted or retreats earlier than anticipated[1].

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 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.

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.

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.

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.