Highest temperature in London on June 27?

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Active sub-markets

Market context

On 27 June 2026, London City Airport faces a day where the highest recorded temperature will determine the outcome of a prediction market, with the crowd currently assigning zero probability to any outcome above the lowest range. This 0% YES stance reflects a market that has not yet priced in the possibility of a heat spike, despite recent meteorological trends showing London entering its warm season from mid-June with average highs exceeding 67°F. Historical data from the Met Office and BBC Weather indicates that June 27 has previously seen maximum daytime temperatures reach 32°C, with some years recording 31°C under sunny intervals, suggesting that a 0% probability for higher ranges may be an overcorrection if a heatwave develops.

The key catalyst for traders is the potential for a red heat warning, as the UK recently experienced a historic heatwave with temperatures hitting 36.1°C on 24 June, breaking records for the hottest June day ever. Traders should monitor announcements from the Met Office regarding heat alerts and the daily weather forecast for London City Airport, which currently predicts sunny intervals and a high of 31°C. A recent BBC Weather report notes falling pressure and high pollen, conditions that often precede temperature spikes, while Wunderground data confirms that London City Airport has recorded maximums up to 32°C in past June 27 observations. The settlement window ends at 12:00 UTC on 27 June 2026, meaning any temperature surge before noon will directly impact the market resolution.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on June 27? 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 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.

Is this market available outside the US?

PolyGram 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.

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.