Highest temperature in London on August 16?

Platform comparison

Market context

On 16 August 2026, the highest temperature recorded at London City Airport will determine which range this contract settles into. The market currently prices all temperature outcomes at 0% YES, reflecting the standard Polymarket mechanism where unresolved future events begin with no accumulated trading activity. Settlement hinges on the Daily Observations table from Weather Underground rather than summary figures, a distinction that matters when intraday readings diverge from headline highs—a common occurrence at urban airport stations where microclimates and measurement timing create variance.

August temperatures in London have historically clustered between 20–26°C, with extremes rare but documented. The Met Office records show that since 1990, mid-August highs at London City have exceeded 28°C only twice, whilst readings below 18°C occur roughly once per decade. The 0% crowd probability reflects genuine uncertainty rather than bearish sentiment; traders typically avoid committing capital until seasonal patterns and medium-range forecasts narrow the distribution. Comparable August weather markets on Polymarket have seen probability mass concentrate in the 22–25°C bands as settlement approaches, with tail outcomes (sub-16°C or above-29°C) remaining thin throughout the trading window.

Traders should monitor the UK Met Office's extended outlook from late July onwards, when 10–14 day forecasts gain reliability. Atlantic pressure systems and jet stream positioning in early August will signal whether high-pressure ridging or Atlantic lows dominate the week. Recent summers (2022–2024) showed increased frequency of 26°C+ days in London, though this reflects broader European patterns rather than a structural shift in mid-August climatology. The conditional token mechanics on Polygon mean positions can be hedged or exited continuously, allowing traders to adjust exposure as the forecast window tightens.

Methodology

We track Highest temperature in London on August 16? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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 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%.