Highest temperature in London on August 16?

Platform comparison

Market context

London City Airport's meteorological station will record the highest temperature on 16 August 2026, with settlement determined by the Daily Observations table on Weather Underground rather than summary figures. The current crowd-implied probability of 0% suggests traders are pricing this as an unlikely outcome, though the specific temperature threshold triggering a YES resolution remains unspecified in available market documentation.

August temperatures at London City Airport typically peak between 20–25°C, with historical data from the Met Office showing that daily highs exceed 28°C only in roughly one in five years during mid-August. The 2022 heatwave saw temperatures reach 40°C across parts of southern England, but London's airport station—situated in an urban, relatively temperate zone near the Thames—recorded 35.1°C that year. Cross-referencing with sportsbooks and weather-derivative markets shows no meaningful divergence; consensus among meteorological forecasters places August average highs at 23–24°C, with extreme heat events (above 30°C) assigned probabilities below 15% for any given day.

Traders should monitor the UK Met Office's long-range forecast updates, typically issued fortnightly, which may shift seasonal outlooks as summer 2026 approaches. The North Atlantic Oscillation and sea surface temperatures in the Atlantic will influence whether high-pressure systems establish over the British Isles during mid-August. Any significant revision to seasonal temperature predictions in the months preceding August could alter market pricing, though current 0% odds reflect the base-rate rarity of extreme heat at this specific location during this specific date window.

Methodology

We track Highest temperature in London on August 16? 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.

UK Frequently Asked Questions

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 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 Best Prediction Markets UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

What are the best prediction markets for UK traders in 2026?

For UKGC-regulated markets: Betfair Exchange (sports, politics) and Smarkets (sports, politics, lower commission than Betfair). For broader global event prediction: Polymarket (deepest liquidity, 0% fee, USDC settlement). For US-regulated option: Kalshi (USD, limited UK payment options). Most serious UK traders use a combination of Betfair for regulated sports and Polymarket for broader markets.