Highest temperature in London on August 6?

Platform comparison

Market context

Polymarket currently prices this London City Airport temperature contract as a very low-probability bet on an unusually warm reading, with the market showing **0% YES** in crowd terms despite the live order book still assigning outcomes across the low- to mid-20s Celsius range. Because the market resolves to the **highest** temperature recorded at London City Airport Station on 6 August and pays out in USDC via Polygon-settled conditional tokens, the relevant question is not whether London is warm in general, but whether the day’s peak lands in a specific whole-degree Celsius band before the noon UTC settlement cut-off.[3]

Historical context argues against treating 0% as a stable forecast. London’s August climate normally sits around the high teens to low 20s Celsius, while forecast products for early August have recently clustered around the low-to-mid 20s, including 22°C and 23°C as the leading Polymarket outcomes and 75°F/24°C-type highs in commercial weather feeds.[1][3][7][12] That leaves the market sensitive to even modest forecast revisions: on days when southern England is influenced by hotter air, London can jump several degrees above seasonal norms, and the city has already seen 2026 heat spikes in the wider region.[14][15][16]

For traders, the main catalysts are the morning forecast updates, any Met Office or model-driven changes to the expected daily maximum, and the actual observed reading at London City Airport as the day unfolds. The contract cannot resolve until the resolution source has published the first data point for the following date, so the final price is shaped as much by timing and station-specific reporting as by headline London weather.[3] With the market tied to a single airport station and a whole-degree Celsius source, the practical watchlist is simple: forecast shifts, realised daytime heating, and any late surge around the usual afternoon maximum window.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on August 6? 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

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 does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

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%.