Highest temperature in London on August 9?

Platform comparison

Market context

Polymarket is pricing this London City Airport temperature contract at **31°C** with the **0% YES** crowd view sitting against that band, which leaves the market effectively assuming the day’s peak will land there unless the afternoon observation pulls materially higher or lower.[4] Because settlement uses the **Wunderground Daily Observations** table rather than the summary “Day High & Low” figure, traders should watch the recorded station maximum on the official daily page rather than headline forecast snippets; shares are held in USDC on Polygon and settle through the matching conditional token once the outcome is fixed.[4]

Recent weather context gives this contract a hot-weather bias, not a cool one. London saw a renewed heatwave pattern over 8–9 August, with regional highs around **31°C to 32°C** across London and the South East, while forecasts published for 9 August also pointed to highs around **31°C–32°C**.[3][5][8] That sits above London’s August average climate range, but below the extreme national records, so a mid-30s print would need an additional surge in local warming rather than just a normal summer day.[9][14]

For a trader, the main catalysts are intra-day: sunshine, cloud cover, and any late-afternoon thermal peak at London City Airport before the settlement window closes at **12:00 UTC**. The most relevant dependency is the station’s actual logged maximum in Wunderground’s daily observations, so forecast updates matter less than what the airport thermometer records during the day.[4] If the heat persists as reported in broader UK coverage, the market’s current tight pricing can move quickly on even small changes in expected peak temperature.[18][12]

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 Polymarket Alternative UK, which mirrors the Polymarket order book directly.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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%.