Highest temperature in London on August 10?

Platform comparison

Market context

Polymarket has this contract marked at **0% YES**, so the crowd is currently assigning no probability to a London City Airport daily maximum landing in the contract’s winning range. On Polymarket, buyers post and match orders in USDC on Polygon, and the price reflects the market’s real-time view of the chance that Weather Underground’s London City Airport station prints a highest temperature within the relevant Celsius bucket before settlement.

That zero price sits against a fairly ordinary late-summer London backdrop, but August can still produce sharp upside surprises. London’s August records show that the city has reached **32.6°C** in August 2026 so far, while the long-run August maximum for London is far higher, and the UK’s broader August record is **38.5°C** on 10 August 2003, with London stations also featuring in that day’s extremes.[11][12][16] For a contract settling to a specific range, traders usually focus less on the headline city forecast and more on whether the airport station can overshoot into the next bracket, especially if short-range model guidance shifts hotter in the last 24-72 hours.

The key catalysts are the morning and early-afternoon forecast updates, any change in cloud cover or wind, and whether sunshine persists long enough for Heathrow-style inland heating to translate to the airport station; Weather Underground’s daily observations table, not the summary high/low panel, controls settlement.[5] Because the market only resolves on the final daily observation for London City Airport, any late revision to the station record can matter until the next day’s first datapoint is published.[5]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on August 10? 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.

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 Kalshi UK. 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%.