Highest temperature in Seattle on July 22?

Platform comparison

Market context

Seattle’s highest temperature on 22 July is the settlement driver here, using the Seattle-Tacoma International Airport Station reading that Wunderground records for the day. The current prediction-market pricing is starkly one-sided: Polymarket shows **94–95°F** as the frontrunner at **100%**, with **83°F or below** at **0%**, so there is no meaningful divergence in implied probability to compare against a live sportsbook-style line at present.[1]

That 100% reading should be read against Seattle’s summer temperature distribution, where the decisive variable is usually whether a warm, dry inland flow reaches the coast and keeps overnight cooling limited. In practical terms, traders tend to focus less on the calendar date itself than on whether the broader Pacific North-West pattern supports a hot ridge, because once Seattle is under a strong high-pressure dome, airport highs can move rapidly into the 90s and compress the probability ladder around the top bracket. The present contract therefore looks priced as a clean weather hold, rather than a contested forecast with several plausible bins.

The main catalysts to watch are the short-range weather model runs and any forecaster updates on ridge strength, cloud cover, and marine influence, because those determine whether the airport clears into the mid-90s or falls back into a lower bracket. Since the market has already resolved to a single dominant bucket on-platform, the only meaningful trading risk now would be an operational one: a late adjustment in official history data from the reporting station or a revision in the settlement interpretation, rather than a normal forecast swing.[1]

Sources: 1

Methodology

We track Highest temperature in Seattle on July 22? 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

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.

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.

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.