Highest temperature in Seattle on August 4?

Platform comparison

Market context

Polymarket is effectively pricing this KSEA temperature contract at a **0% yes** outcome for the moment, with traders assigning no live probability to the event settling in the “yes” bucket. On-chain, that means positions are being valued in USDC on Polygon, with the contract’s conditional tokens reflecting the crowd’s view of where the Seattle-Tacoma International Airport Station’s top reading on 4 August will land.

The market is best read against Seattle’s August climate rather than a single forecast swing. Long-run normals show August as one of the city’s warmer months, but still generally moderate by US standards, which is why outcomes clustered in the upper 70s or low 80s often dominate pricing when heat is forecast[8][13]. Polymarket’s own event page has shown the crowd converging on an 80–81°F outcome near certainty, while comparable prediction venues for the same date have also been anchored around the low-to-mid 80s, suggesting traders see limited room for an extreme miss unless a forecast busts materially[2][4].

What matters now is the intraday weather chain: National Weather Service updates, the airport station’s observed highs, and whether any late-day sea-breeze or marine-layer effects cap the maximum before the first reading for 5 August is published. The settlement rule is mechanical and depends on the Weather Underground history page for KSEA, so traders watch not just the forecast but the final recorded daily high and the publication of the next day’s first datapoint. In practice, that means even a small shift in the airport observation sequence can determine which temperature band wins the conditional tokens.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in Seattle on August 4? 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 PolyGram, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

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.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like PolyGram trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.