Highest temperature in London on July 14?

Platform comparison

Market context

On 14 July 2026, the highest temperature recorded at London City Airport will fall into one of several defined ranges. The settlement hinges on data pulled from Weather Underground's historical records for that specific station, which sits in the Isle of Dogs and typically captures readings representative of central London conditions. Traders will need to cross-reference the final recorded high against the range brackets on settlement day, with the window closing at noon UTC.

July temperatures in London have historically clustered between 20–25°C, though extremes do occur. The Met Office's 30-year climate average for mid-July sits around 23.5°C, with record highs for the month reaching 34.3°C (set in 2022). The current 0% implied probability on higher ranges suggests the crowd expects a typical summer day rather than a heatwave scenario. Comparable markets on UK temperature extremes have shown systematic underpricing of tail outcomes during El Niño or Atlantic blocking patterns, which can persist into mid-summer.

Traders automating this market should monitor the UK Met Office's extended forecast and Atlantic sea surface temperature anomalies from late June onwards. The North Atlantic Oscillation index and jet stream positioning in early July will signal whether high-pressure systems favour continental heat advection into the British Isles. Weather Underground's historical data feed updates daily, allowing conditional orders or bot-triggered alerts if forecasts shift materially. Note that airport station readings can diverge from urban heat island effects measured elsewhere in London, a factor worth isolating when backtesting similar markets.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Kalshi Fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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 Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

Do I need to KYC for this market?

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