Highest temperature in London on August 7?

Platform comparison

Market context

Polymarket has this London temperature contract priced at **0% YES** right now, which means the market is assigning no value to the target temperature band being hit before the settlement window closes. Because the contract settles on the **highest reading in Weather Underground’s Daily Observations table** for London City Airport on 7 August, not the headline “Day High & Low” figure, the live tick matters more than the day’s summary screen, and conditional tokens on Polygon will resolve against that source if there is any mismatch.

The current pricing sits against a fairly ordinary August baseline rather than an extreme-heat setup. Forecast material for London on 7 August points to highs around **25–26°C**, which is consistent with a modest summer day and well below the hotter bands that usually attract stronger odds in temperature markets[1][4][12]. That matters for reading the zero price: in these contracts, the absence of a credible path to a higher band often leaves the book anchored at the lowest or nearest range, even if midday conditions look warm on the ground.

For traders, the practical catalysts are the late-day temperature trace, any short-lived spike at London City Airport, and whether forecasters start upgrading the weekend pattern towards hotter air. Several outlets have flagged a warmer turn after Friday, with one report saying London could reach **28°C or more** from Saturday as a broader UK heatwave builds[10][13]. That does not affect today’s settlement directly, but it frames the near-term weather regime and explains why the market can still move if the airport station briefly outperforms the city forecast or a late-afternoon surge appears in the observations.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in London on August 7? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Kalshi UK, which mirrors the Polymarket order book at 0% fees.

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.

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%.