Highest temperature in London on August 16?

Platform comparison

Market context

The contract settles on the highest temperature recorded at London City Airport on 16 August 2026, measured in degrees Celsius via Weather Underground's Daily Observations table. Polymarket currently prices this at 0% YES, indicating the crowd assigns negligible probability to the specific outcome this range represents. The settlement mechanism relies on granular hourly data rather than summary figures, a distinction that matters when temperature swings occur within a single day—particularly relevant for London's maritime climate, where afternoon peaks often diverge substantially from daily maximums reported in conventional forecasts.

August temperatures at London City Airport typically range between 18–24°C, with historical highs occasionally reaching 27–28°C during heat waves. The 2022 summer heatwave saw UK temperatures exceed 40°C, though London itself remained below 35°C. More recently, August 2023 brought moderate conditions with peaks around 22–24°C. The 0% pricing suggests either this particular temperature band falls well outside plausible ranges for mid-August, or traders have already concentrated liquidity on adjacent ranges, leaving this one undervalued relative to tail-risk scenarios.

Key variables affecting the outcome include Atlantic weather systems and high-pressure systems tracking across the continent in early-to-mid August 2026. The Met Office's seasonal outlooks, typically issued in July, will provide initial guidance on whether conditions favour above or below-average temperatures. Traders should monitor European weather models from mid-July onwards, as these offer the most reliable 10–15 day forecasts. Any significant heatwave developing across continental Europe in early August would increase the probability of elevated readings at London City Airport by the 16th.

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

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.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

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%.