Highest temperature in London on August 17?

Platform comparison

Market context

On 17 August 2026, the highest temperature recorded at London City Airport will determine which range this contract settles into. The market currently prices all temperature bands at 0% YES, reflecting the standard state of unresolved future weather events on Polymarket before meaningful price discovery occurs. Settlement hinges on the Daily Observations table from Weather Underground rather than summary figures, a distinction that matters when intraday temperature swings produce discrepancies between peak readings and reported highs.

London's August temperatures have historically clustered between 20°C and 26°C, with extremes rare but documented. The summer of 2022 saw the UK record 40.3°C during an exceptional heatwave, though London itself peaked lower. City Airport, situated in the Docklands with urban heat island effects, typically registers slightly warmer readings than surrounding areas. August 2023 brought highs around 24–25°C to the capital, whilst 2024 remained broadly temperate. These precedents suggest most probability mass should concentrate in the 22–28°C ranges, with tail outcomes above 30°C or below 18°C carrying minimal historical support.

Traders should monitor the Met Office's seasonal forecasts and Atlantic weather patterns as summer 2026 approaches. Persistent high-pressure systems or blocking patterns could drive sustained warmth, whilst Atlantic low-pressure systems would suppress temperatures. The UK's climate trajectory shows gradual warming, though individual August days remain unpredictable. Real-time conditional token mechanics on Polygon mean early positions establish baseline pricing; liquidity typically deepens as the settlement date nears and forecast confidence improves.

Methodology

We track Highest temperature in London on August 17? 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

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 PolyGram. 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 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 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.