Highest temperature in London on June 24?

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Market context

The real-world event is the highest temperature recorded at London City Airport on 24 June 2026, measured in degrees Celsius and resolved via Wunderground data. This single metric determines the market outcome, with the current crowd-implied probability of 76% favouring a result of 35°C or below. Historically, late June in London rarely exceeds 35°C; the warm season begins mid-June with average daily highs above 20°C, but extreme heat events are uncommon. For instance, a recent record-breaking day saw 38°C, which was deemed abnormal for late June and broke the June maximum temperature record, highlighting that such extremes are outliers rather than expectations[7]. The current 70% probability assigned to the 35°C or below outcome aligns with this historical pattern, suggesting the market is pricing in typical summer conditions rather than a heatwave[1].

A power-user evaluating this market programmatically would monitor real-time weather feeds from the Met Office and BBC Weather, focusing on forecasted high temperatures, wind speed, and humidity levels for the specific date. Key catalysts include any sudden shifts in atmospheric pressure or the development of southerly winds, which can drive higher temperatures. Traders should watch for official weather warnings issued by the Met Office, as these often precede extreme heat events. Recent commentary from weather experts notes that 38°C is not normal for late June, reinforcing the need to track forecast updates closely rather than assuming a heatwave[7]. Programmatically, one would set conditional orders based on Wunderground’s hourly temperature data, ensuring trades are executed only when forecasts indicate a sustained rise above 35°C. The settlement window ends at 12:00 UTC on 24 June 2026, so all data must be captured before this deadline.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

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'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 Polymarket App UK?

Zero. Polymarket App 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, Polymarket App UK triggers a quick verification flow that finishes in minutes.