Highest temperature in Seattle on August 10?

Platform comparison

Market context

Polymarket is pricing the Seattle airport temperature contract at **0% YES**, with conditional tokens on Polygon implying the market sees virtually no chance of the eventual daily maximum landing in the specified outcome range. The settlement will hinge on the highest reading in Weather Underground’s Daily Observations for Seattle-Tacoma International Airport, so traders are effectively holding USDC-backed exposure to a single station print rather than the broader city forecast or the Day High & Low summary.

That zero price sits against a record that is not especially supportive of extremes, but August in Seattle does occasionally produce sharp spikes. The hottest August day on record reached **99°F**, and August 10 has historically posted highs as strong as **98°F** and **95°F** in prior years, while the long-run average high for that date is about **77.5°F**[1][3][16]. Recent forecast services also pointed to a much milder setup around the low-to-mid 70s for August 10, which is consistent with why traders have pushed the contract towards the floor rather than pricing in a late heat surge[4][12][17].

A trader watching the final path would focus on the day-of forecast convergence, any abrupt warm-air advection into western Washington, and, most importantly, the actual hourly observations at Sea-Tac, because the market resolves from the recorded daily maximum rather than the headline forecast or summary display. The practical catalyst is whether late-day warming, downslope flow, or a forecast bust nudges the station reading into a higher bucket; absent that, the on-chain payout stays aligned with the currently dominant cool-price structure rather than a rare August outlier[5][13].

Sources: 1 · 2 · 3 · 4 · 5

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 PolyGram, which mirrors the Polymarket order book directly.

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

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 PolyGram. 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 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.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

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.