Highest temperature in London on June 26?

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Market context

The real-world event is the daily high temperature at London City Airport on 26 June 2026, which will determine the outcome of a prediction market where the crowd currently assigns zero per cent probability to the “YES” side. This implies traders believe the temperature will fall outside the specified range, despite June typically bringing summer warmth to the capital.

Historical data frames this near-zero probability as an outlier. In June 2026, Kew Gardens in southwest London recorded 26.6°C on 24 June, the hottest day of the year so far according to the Met Office[3][7]. London City Airport’s own recent high was 79°F (26.1°C) on the same day[4], while the average June high in London is only 21.3°C[6]. Given that temperatures have already exceeded 26°C this month, a zero per cent implied probability suggests the market expects a sharp, unseasonal drop rather than a continuation of the current warm trend.

Traders should monitor the Met Office’s daily forecasts and any sudden shifts in atmospheric pressure or cloud cover expected over the next 24 hours. The settlement window closes at 12:00 UTC on 26 June, meaning morning conditions will be decisive. No major weather announcements are scheduled, but real-time updates from the National Weather Service for EGLC will be critical as the day progresses[2]. Any divergence between sportsbook lines on similar heat contracts and this prediction market’s zero per cent line may signal a mispricing worth investigating.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on June 26? 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

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 Best Prediction Markets 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.

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 Best Prediction Markets UK?

Zero. Best Prediction Markets UK 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.