Highest temperature in London on August 8?

Platform comparison

Market context

London’s temperature on 8 August is what Polymarket is pricing here, with the contract currently showing **0% YES** even though the settlement rule depends on the highest reading in Weather Underground’s Daily Observations for London City Airport. In practice, traders are buying and selling conditional tokens on Polygon using USDC, so the market is effectively a live consensus on which Celsius band the airport station will print before the noon UTC cut-off.

The historical frame points to how volatile London summer heat can be. Weather-history pages for 8 August show forecast highs in the low 20s Celsius, while recent London heat coverage and UK heat-health alerts underline that sharp spikes are possible when the city sits under a warm, dry air mass.[7][9][13] A recent Polymarket London temperature market for 1 August also resolved at the upper end of the range, with the platform’s market page showing the 26°C bracket at 100% before settlement, which is a reminder that these contracts often tighten quickly once the day’s actual readings start to firm up.[8]

For traders, the main catalysts are the intraday observations at London City Airport, not the broader London forecast alone. AccuWeather and similar forecast pages suggested a warm 8 August, with daytime highs around 29°C to 31°C, while Weather Underground’s own daily record for the airport is the settlement source that matters if a late peak lands in a higher band.[1][14][8] The UKHSA yellow heat-health alert in force for London from 8 August also signals a setup where the day could stay elevated rather than cool rapidly, which is relevant for the final observed maximum.[9]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on August 8? 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

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 Polymarket Scam?. 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.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.