Highest temperature in London on August 15?

Platform comparison

Market context

The market resolves on the peak temperature recorded at London City Airport on 15 August 2026, measured in degrees Celsius via the Daily Observations table on Weather Underground. Settlement occurs in USDC against the specific temperature range bracket that captures the day's high, with the resolution source explicitly prioritising the granular observation data over summary figures.

August temperatures at London City Airport typically range between 18–25°C, with historical August averages clustering around 20–22°C. The 0% implied probability suggests traders are pricing in an extremely low likelihood of an exceptionally high reading—well above the typical summer ceiling. Comparable August days over the past decade show that readings exceeding 28°C are rare but not unprecedented; the 2022 heatwave saw London record 40.3°C, though City Airport's microclimate and measurement protocols often yield lower figures than central London sites. This baseline context indicates the crowd is either anchored to normal seasonal patterns or expects cooler-than-average conditions in summer 2026.

Key variables affecting settlement include Atlantic weather patterns, jet stream positioning, and any high-pressure systems tracking across the UK in mid-August. The Met Office's seasonal outlooks and European model consensus runs become material reference points as the settlement window approaches. Traders should monitor early-August 2026 temperature trends and any official forecasts issued in the days preceding 15 August, as short-range weather models typically stabilise 7–10 days out. The specificity of the Weather Underground Daily Observations source means settlement hinges on precise instrumental readings rather than interpolated estimates, making the exact station location and measurement methodology critical to outcome determination.

Methodology

This page reads Highest temperature in London on August 15? on-chain. Polymarket's quote comes directly from the Polygon order book — the only comparable venue with on-chain settlement. Kalshi (USD, off-chain), Betfair (GBP/EUR, off-chain) and Manifold (play-money) are listed alongside for venue context. Every CTA routes to BTC Prediction, which mirrors the Polymarket order book directly.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

UK Frequently Asked Questions

What are crypto prediction markets?

Crypto prediction markets are on-chain smart contracts where you buy YES or NO shares on a future crypto event (e.g. "BTC above $100k by year-end"). The market price between 0¢ and 100¢ is the implied probability.

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No, Polymarket operates exclusively in USDC on Polygon. You can bridge BTC to USDC via an exchange or bridge service and deposit on Polygon — typically 10-30 minutes processing time.

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%.