Highest temperature in Seattle on August 10?

Platform comparison

Market context

Seattle's daily maximum temperature on 10 August 2026 will be recorded at Seattle-Tacoma International Airport, with settlement determined by the granular 'Daily Observations' table on Weather Underground rather than the rounded summary figures. The market bins outcomes into temperature ranges, and the current 0% probability on the YES option suggests traders are pricing in either a specific threshold being unlikely or significant uncertainty about which range will resolve. This is a straightforward instrumental market: the event occurs, the data is published within hours, and resolution follows a single authoritative source with minimal interpretation required.

Historical August temperatures at Sea-Tac show a median high around 79°F, with the airport's all-time August record of 96°F set in 1981. The past decade's August highs have clustered between 75–85°F, with occasional excursions to 88–90°F during Pacific Northwest heat waves. Traders evaluating this market should cross-reference climatological patterns: if the YES range sits above 90°F, the 0% probability reflects the statistical rarity of such extremes in August, whereas a range of 70–75°F would suggest the crowd expects cooler-than-typical conditions.

For programmatic traders, the key dependency is NOAA's extended forecast release cycle and any atmospheric pattern shifts signalled by the Climate Prediction Center in the weeks preceding August. The National Weather Service Seattle office publishes detailed discussions that often flag heat potential 10–14 days out. Weather Underground's API integration allows automated monitoring of historical station data quality and any sensor anomalies that might affect resolution integrity, particularly important given the market's explicit reliance on the Daily Observations table rather than summary fields.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

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 Polymarket Review UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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%.