Highest temperature in London on June 26?

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Active sub-markets

Market context

The highest temperature recorded at London City Airport on 26 June 2026 will determine the outcome of this prediction market, with the current crowd-implied probability for a "Yes" on the 32°C or below range sitting at 0%. Polymarket prices this contract today with $22,612 in volume on the 32°C or below outcome and $25,383 on the 33°C tier, while the frontrunner is 35°C at 37%, followed by 36°C at 26%. These odds shift in real-time as traders execute trades using USDC on the Polygon network via conditional tokens, reflecting the collective view of what is most likely to occur.

Historical June data frames how to interpret this near-zero probability for cooler outcomes. London City Airport’s warm season begins 16 June, with average daily highs exceeding 67°F (19.4°C), and recent records show 33.9°C at Heathrow making it the hottest June day since 1976, while a provisional 35°C was recorded at Kew Gardens in May. The Met Office currently forecasts 36°C for London City Airport today, suggesting that temperatures in the 35–36°C range are consistent with recent extreme June weather patterns rather than outliers.

Traders should monitor the Met Office’s hourly forecast updates and Wunderground’s real-time station data, as the market resolves only after the first data point for 26 June is published. The Met Office forecast for 26 June lists 36°C, with a sharp drop to 32°C by 27 June, indicating a potential heat peak that aligns with the market’s 35°C frontrunner. A recent BBC Weather observation at 10:00 BST recorded 13°C with 88% humidity and falling pressure, but this early reading is not the daily maximum; the catalyst is the afternoon high, which historically drives June extremes in the UK.

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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

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

Is this market available outside the US?

Kalshi 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.

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 Kalshi UK?

Zero. Kalshi 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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Kalshi UK triggers a quick verification flow that finishes in minutes.