Highest temperature in London on August 7?

Platform comparison

Market context

Polymarket is pricing this London temperature contract at **0% YES**, which on Polygon means the USDC-settled conditional token is still behaving as if a qualifying reading above the relevant threshold is essentially not expected. For a market resolved off Weather Underground’s **Daily Observations** table at London City Airport, that matters more than headline forecasts: the contract will pay only if the day’s recorded peak lands in the specified Celsius band, so traders are really handicapping a station-specific maximum rather than a generic London high.

The historical frame points to a fairly ordinary August profile for London, not a heat-extreme one. Current forecast sources cluster around the mid-20s Celsius, with London models showing highs near 24.7°C to 26.7°C and broader August normals around the low-20s Celsius, while some monthly services put average August highs nearer 22°C to 23°C.[1][3][10] That is consistent with a market starting from a very low implied probability unless a late-summer warm spell pushes the airport station above forecast norms. For context, the nearby Airport station often differs from central London readings by a small but trade-relevant margin, so users generally anchor to the actual observation source rather than city-wide summaries.

The main catalysts are the intraday weather evolution and whether any short-lived afternoon warmth is captured in the Wunderground observations before the settlement cut-off. Forecast services currently point to dry, sunny or partly cloudy conditions with minimal rain risk, which supports a modest warm-up into the afternoon but does not, by itself, imply an extreme reading.[4][7] Traders watching the order book should focus on later forecast updates, any unexpected convective cloud cover, and the final hourly run-up at London City Airport, because the last recorded daily maximum on the observation table is what determines the on-chain payout.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to PolyGram, which mirrors the Polymarket order book directly.

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 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.

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%.