Highest temperature in London on August 17?

Platform comparison

Market context

London City Airport will record a daily maximum temperature on 17 August 2026, with the precise figure determined by the Weather Underground Daily Observations table rather than summary figures. The market currently prices all temperature ranges at 0% probability on Polygon, suggesting either minimal liquidity or a technical issue with the contract's conditional token structure on USDC settlement. This pricing disconnect warrants scrutiny, as August temperatures in London are historically measurable and predictable within established ranges.

Historical August data from London City Airport shows maximum temperatures typically ranging between 20–26°C, with occasional peaks above 27°C during heat waves. The 2022 heatwave pushed readings to 40°C across parts of the UK, though London City Airport recorded 35.4°C on 19 July that year. August 2003 saw sustained highs around 30°C at the airport. Current market pricing at zero across all brackets suggests traders are either awaiting clearer contract terms or treating this as a placeholder until nearer the settlement date.

The UK Met Office publishes extended forecasts roughly two weeks ahead, with increasing accuracy from ten days out. Traders should monitor late July 2026 seasonal outlooks and any Atlantic weather pattern shifts that might drive continental warm air into the UK. The specific reliance on Weather Underground's Daily Observations table—rather than official Met Office or airport records—introduces a minor data-source dependency worth confirming before significant position-taking, particularly given the explicit resolution hierarchy stated in the market terms.

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

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

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 Polymarket Scam?. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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%.