Highest temperature in London on August 8?

Platform comparison

Market context

The relevant real-world event is the highest Celsius temperature logged at London City Airport on 8 August 2026, using Weather Underground’s Daily Observations table as the resolution source. For a programmatic workflow, that means polling the station-day record directly, not relying on the summary high/low tile, and treating later revisions as relevant only until the next day’s first datapoint appears, because the market rules privilege the observation table over the display summary.[1]

A 0% YES price is only defensible if traders are already treating the outcome as fully locked or if the market is mispriced relative to the observation data. A useful analogue is the August 6 London temperature market, which resolved cleanly to 23°C once the station record was confirmed, showing that these contracts can snap to a single bracket when the observed maximum is unambiguous.[16] For historical context, London’s August climatology is usually mid-to-high teens to low 20s, but warm spells are common enough that a 28°C reading is entirely plausible in late summer.[11][12]

The key catalysts are the actual station observations and any late-day revision on Weather Underground, rather than forecast headlines alone. Traders running bots or conditional orders should watch for the first post-midnight UTC update that finalises the Daily Observations table, and should also note that heat alerts can coincide with hotter outcomes, as UKHSA had an active London heat-health alert for 8–11 August 2026.[8] Forecasts published on the day pointed to around 28°C in London, which would place the market in the top bracket if the station matched citywide expectations.[5]

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 Bot 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%.