Highest temperature in London on August 7?

Platform comparison

Market context

London’s peak temperature is the number that settles this contract, using the London City Airport Station reading from Wunderground’s Daily Observations table rather than any headline day-high figure. With the market already implying **0% YES**, the pricing suggests traders see the listed outcome bands as effectively unreachable or already ruled out by the weather setup, which is notable in a city where late-summer highs often cluster in the mid-to-upper 20s Celsius rather than extreme values.[3][11]

The closest historical guide is recent August behaviour in London rather than long-run records: AccuWeather’s monthly outlook has London around the mid-20s Celsius for nearby days, while a local forecast on Friday placed the day’s high at 26°C with little rain risk.[1][4] That sits in line with the broader UK pattern described by the Met Office, which notes summer 2026 maximum temperatures have been above average but not record-breaking season-to-date.[15] For a prediction market, the key point is that settlement depends on a single station observation, so small forecast misses, sea-breeze effects, or a late-afternoon lull can decide whether the final reading lands in one band or the next.

The main catalysts are the intraday temperature curve and any fresh forecast updates from the Met Office or similar forecasters, especially if cloud cover, wind direction, or convective showers shift London’s high away from the consensus range.[11][13][17] On-chain, the trade is a pure USDC settlement bet, so there is no funding-rate mechanics, but broader crypto risk appetite can still shape liquidity and spread width around expiry. If BTC and ETH volatility is elevated, market makers often widen, and that can matter more than the weather itself when the contract is already pinned near the tails.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reads Highest temperature in London on August 7? 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

Why USDC and not ETH or USDT?

USDC is the Polygon standard — audited reserves (Circle, monthly attestation), deepest order book, low gas costs. ETH volatility would distort probability quotes; USDT has thinner Polygon liquidity than USDC.

What does a transaction cost on Polygon?

Polygon gas is typically under $0.01 per transaction. A full trade cycle (Approve + Order + Fill) totals around $0.03 — compared to $5-50 on Ethereum mainnet.

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%.