Highest temperature in Seattle on August 4?

Platform comparison

Market context

Seattle-Tacoma International Airport’s recorded high on 4 August is the settlement driver here, and the market is pricing a **0% YES** chance for the *non-favourite* buckets, with consensus effectively locked on a warm August afternoon. That makes the favourite the mid-80s-to-low-80s band, while the underdog is a materially cooler outcome if cloud, marine push, or an early sea breeze keeps the airport from warming as much as the broader Seattle metro.

Historically, Seattle’s August climate is one of the warmest and driest stretches of the year, with averages around the low-to-mid 70s Fahrenheit and many days clearing into the upper 70s or low 80s rather than staying cool all day.[1][9] Recent market pricing on comparable Seattle daily-high contracts has also clustered around the upper 70s to low 80s, with traders putting heavy weight on the site-specific airport reading rather than downtown conditions.[11] On that framing, the favourite remains the high-80s-adjacent or low-80s outcome, while the contrarian value lies in any setup that caps the airport high below the consensus band.

The main catalysts are the day-of forecast track and the actual observed airport sequence: if morning marine cloud lingers, the ceiling on the high can come down quickly; if sunshine breaks earlier, the market usually grinds towards the consensus band. Traders should watch National Weather Service updates and airport observations through the afternoon, because once the first datapoint for the following date is published, later revisions are excluded from settlement under the market rules.[2] NOAA’s seasonal outlook has also leaned warmer-than-average for the Pacific Northwest, which supports the bullish side for heat outcomes, but it does not remove the usual Seattle downside risk from coastal influence or cloud cover.[17]

Sources: 1 · 2 · 3 · 4 · 5

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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

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 Who Will Win 2026. 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.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Who Will Win 2026 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.