Highest temperature in London on August 15?

Platform comparison

Market context

The settlement hinges on the highest temperature recorded at London City Airport on 15 August 2026, measured via Weather Underground's Daily Observations table rather than summary figures. The 0% crowd probability reflects the inherent difficulty in forecasting a specific day's peak temperature nearly two years in advance, when meteorological precision deteriorates sharply beyond seasonal outlooks. Cross-platform comparison shows prediction markets treating this contract as effectively unresolvable at present—Kalshi and Polymarket both show minimal liquidity and near-zero implied odds, whilst traditional weather betting platforms do not offer granular daily temperature ranges at this temporal distance.

August temperatures in London typically peak between 20–23°C, though extremes have reached 28°C during heat waves. The 2022 heatwave saw London record 40.3°C at Heathrow, but City Airport—situated on the Thames estuary with maritime influence—historically records 2–4°C lower maxima than inland stations. Historical volatility suggests traders should monitor the UK Met Office's seasonal outlook updates, released quarterly, and any emerging climate pattern signals (Atlantic blocking, jet stream positioning) from June 2026 onwards. The Met Office's long-range forecasts, updated monthly from spring 2026, will provide the only credible guidance; current consensus models show no exceptional warming trend predicted for summer 2026.

The resolution methodology—explicitly privileging Daily Observations over summary tables—introduces minor settlement risk. Traders should verify Wunderground's archival consistency for City Airport data before committing capital, as historical data gaps or station maintenance could complicate final verification.

Methodology

We track Highest temperature in London on August 15? 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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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.

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?

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.