Highest temperature in London on August 12?

Platform comparison

Market context

On 12 August 2026, the highest temperature recorded at London City Airport will determine this market's settlement. The contract currently trades at 0% implied probability across all temperature bands, suggesting either extreme uncertainty about which range will resolve or minimal trading activity establishing a price floor. Settlement hinges on the Daily Observations table from Weather Underground rather than summary figures, a distinction that matters when intraday peaks differ from official highs.

London's August temperatures have historically clustered between 20–27°C, with extremes rare but documented. The city recorded 40.3°C in July 2022 during an exceptional heatwave, though August typically remains cooler than peak summer months. August 1990 saw 31.9°C as a notable high; more recently, August 2022 peaked at 35.4°C. These precedents suggest the market's zero probability across all bands reflects either a data lag or the contract's early stage rather than genuine certainty that temperatures will fall outside historical ranges.

Traders should monitor the Met Office's medium-range forecasts from early August 2026, particularly any alerts for heat domes or Atlantic blocking patterns that could drive anomalous warmth. The UK's summer weather remains sensitive to jet stream positioning and sea surface temperatures in the North Atlantic. Any official heatwave warnings issued by the UK Health Security Agency would signal elevated risk for temperatures exceeding 30°C. Settlement depends entirely on the Weather Underground station data, so traders verifying the specific sensor location and its historical calibration against other London weather stations could identify basis risk before committing USDC on Polygon.

Methodology

We track Highest temperature in London on August 12? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.