Platform comparison
| Platform | YES odds | NO odds | Fee | KYC | Settlement | |
|---|---|---|---|---|---|---|
Polymarket (via Prediction Today) Pick polygram.ink (preferred broker) |
45% | 55% | 0% (USDC on-chain) | No-KYC up to $1,500 | USDC, auto via UMA oracle | Live odds → |
Polymarket (direct) polymarket.com |
45% | 55% | 0% | Geo-blocked in US/UK/EU | USDC, on-chain | Live odds → |
Kalshi kalshi.com |
— | — | Up to 7% per trade | US-only, KYC required | USD | Live odds → |
Betfair Exchange betfair.com |
— | — | 2-5% commission | Full KYC from first trade | GBP / EUR | Live odds → |
Manifold Markets manifold.markets |
— | — | Play-money (mana) | None — play-money | Mana (no cash-out) | Live odds → |
Outcome probabilities
Current market-implied probability for each outcome, from the live order book.
| Outcome | Probability |
|---|---|
| 25°C | 45% |
| 24°C | 36% |
| 26°C | 13% |
| 23°C | 10% |
| 22°C | 1% |
| 27°C | 1% |
| 20°C or below | 0% |
| 21°C | 0% |
| 28°C | 0% |
| 29°C | 0% |
| 30°C or higher | 0% |
Market context
London's weather on 11 August 2026 will be determined by atmospheric conditions roughly two years hence, making near-term forecasting irrelevant. The 0% crowd probability reflects the market's current inability to predict specific temperature ranges that far ahead; meteorological skill deteriorates sharply beyond ten days, and seasonal outlooks carry substantial uncertainty bands. August in London typically sees daily highs between 20–24°C, though extremes have ranged from 13°C to 37°C across the historical record.
The 2022 heatwave, which pushed London to 40.3°C in July, demonstrated how rare but plausible heat events can occur during summer months. However, such extremes remain statistical outliers; August temperatures exceeding 30°C happen roughly once per decade. The market's current pricing suggests traders are anchoring to typical August conditions rather than assigning meaningful probability to either unusually warm or cold scenarios two years out.
Traders monitoring this market should note that long-range seasonal forecasts from the Met Office or European Centre for Medium-Range Weather Forecasts (ECMWF) will become marginally more informative only in late July 2026, when ten-day forecasts begin converging on actual conditions. Until then, the market will primarily reflect base-rate assumptions about August climatology rather than genuine predictive information. Resolution will depend on Weather Underground's Daily Observations table for London City Airport, which may occasionally diverge from other reporting stations across the capital.
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 Prediction Today, which mirrors the Polymarket order book directly.
Resolution & payout
Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.
Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.
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.
- 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%.
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