Highest temperature in London on August 12?

Platform comparison

Market context

On 12 August 2026, the highest temperature recorded at London City Airport will determine the settlement of this market. The contract resolves to whichever temperature band contains the peak reading from Weather Underground's Daily Observations table—the granular station data rather than summary figures. Currently, Polymarket prices all temperature ranges at 0% YES across the board, indicating either a technical glitch in the interface or genuine uncertainty about which bracket will ultimately contain the day's maximum. USDC settlement on Polygon means traders holding conditional tokens for the correct range will receive redemption value only if their band matches the official reading.

London's August temperatures have historically clustered between 20–28°C, with extremes rare but documented. The Met Office recorded 34.4°C in August 1990 and 32.4°C in August 2022, establishing that heat waves do occur during this month, though they remain statistical outliers. City Airport's microclimate—positioned near the Thames with urban heat island effects—typically runs 1–2°C warmer than central London averages. The 0% probability across all ranges suggests traders may be awaiting clearer seasonal forecasts or waiting for the market to populate with more granular temperature bands before committing capital.

The UK Met Office publishes extended forecasts roughly two weeks ahead, with meaningful updates arriving in late July 2026. Traders should monitor any Atlantic weather patterns that could drive high-pressure systems over the British Isles during early August, as such systems consistently produce the warmest readings. The settlement window closes at 12:00 UTC on the day itself, giving traders no opportunity to adjust positions after the morning forecast updates.

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 Polymarket Scam?, which mirrors the Polymarket order book directly.

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%.