Highest temperature in Seattle on August 5?

Platform comparison

Market context

Seattle-Tacoma International Airport’s afternoon maximum on 5 August is the settlement variable, so the practical task is to map the day’s observed high at KSEA to the market’s temperature band rather than to any citywide reading. The 0% crowd-implied YES figure is therefore best read as a stale or mis-specified price signal until the actual Wunderground history page is checked, because the contract resolves from the airport station’s recorded daily high, not a forecast headline or nearby neighbourhood weather. [10][2]

For context, Seattle’s early-August highs are usually in the upper 70s to low 80s Fahrenheit, with AccuWeather’s August outlook showing nearby dates clustered around 80–82°F, and historical climate pages describing August as a comparatively warm but not extreme month. That matters for programme-driven trading: a rules-based bot would typically ingest hourly observations, wait for the day’s maximum to stabilise, and then assign the band most consistent with the airport reading; in a quiet August setup, the main uncertainty is whether the high lands in the low 80s or pushes into a hotter bracket. [1][6][16]

The catalysts to watch are the usual ones for a single-day weather market: the forecast path for daytime warming, marine-layer timing, and any heat-related advisories that could indicate stronger inland heating. A recent example of that setup is a heat advisory issued for parts of the region on 5 August in the broader Seattle-area forecast cycle, showing how a marginally warmer pattern can still matter for the daily high even when the city looks moderate on paper. For a trader using alerts, conditional orders, or copy-trading, the cleanest workflow is to monitor the airport station’s observed peak through the afternoon and avoid anchoring on forecast graphics that may differ from the settlement source. [7][12][10]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in Seattle on August 5? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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

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.

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.