Highest temperature in Seattle on August 5?

Platform comparison

Market context

Polymarket has this contract at **0% YES** today, which means the crowd is effectively pricing a sub-range outcome rather than a materially hot August peak, even though the market settles off the highest temperature recorded at Seattle–Tacoma International Airport and not the citywide feel. On Polymarket, traders are swapping USDC on Polygon into conditional tokens, so the quoted price is the market’s live view of where the official Wunderground reading will land when the day is fully complete.

For context, Seattle’s August highs are often in the upper 70s to low 80s Fahrenheit, but the distribution can widen quickly when a warm spell builds in the Pacific Northwest. Wunderground’s KSEA history for early August 2026 already showed a 24-hour high of 84.0°F on 1 August, while market pricing on the closely related 4 August contract had concentrated around the mid-80s bands rather than the extreme top end. That is the right frame for a 0% yes price here: not a forecast of impossibility, but a sign that traders see the hottest reading on 5 August as more likely to settle below the highest bands than to reach them.

The main catalysts are the same ones weather desks watch in real time: revised National Weather Service guidance, the overnight and morning KSEA observations, and whether any heat advisory or marine-layer breakdown develops before the airport’s daily maximum is locked in. Weather.com and NWS products can shift quickly when inland heat and onshore flow compete, and that is what typically moves these contracts rather than the calendar date itself. Because settlement depends on the final Wunderground daily table for KSEA, traders will usually watch for late-day updates and the first observation of the following day, which confirms the completed high.

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Methodology

This page reviews Highest temperature in Seattle on August 5? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Polymarket Scam?, which mirrors the Polymarket order book at 0% fees.

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

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%.