Highest temperature in Seattle on July 22?

Platform comparison

Market context

Seattle’s hottest reading on 22 July will be set by the Sea-Tac airport station figure on Wunderground, so the market is really about where the day’s maximum lands rather than the city headline temperature. A 0% crowd price on Polymarket signals that traders currently see the listed band as effectively unreachable, but that is not the same as zero chance on Betfair or Smarkets, where odds are expressed in decimal form and the same weather outcome can look different once commission is included. Polymarket’s menu of temperature bands also means pricing can shift sharply between adjacent ranges if forecasts move a degree or two.

Historically, Seattle’s late-July highs are often close enough to the low- to mid-80s that a forecast miss of several degrees can change the winning band, especially if marine air arrives late or the afternoon heating peaks earlier than expected. For comparison, AccuWeather had Seattle around 70°F in the morning at the time of checking, which is far below the sort of values needed to support a top-end outcome on this market.[2] On platforms such as Kalshi, the same event would be constrained by U.S. account access and KYC, while Betfair and Smarkets typically reach a different customer base and can reflect fees differently in the quoted price.

The key catalysts are the local forecast updates, any changes in marine layer timing, and whether winds remain light enough for inland warming to build through the afternoon. Traders will also watch for any shift in the Airport station’s observed temperature path, since the settlement is based on the day’s recorded high rather than a forecast or downtown reading. Polymarket’s current book is therefore sensitive to short-term model revisions, while on Betfair and Smarkets the same weather view may trade at a slightly different effective price because the display is odds-led rather than direct probability-led.

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Methodology

We read Highest temperature in Seattle on July 22? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live mid is the canonical probability; the side-by-side columns benchmark fees, KYC, settlement currency and deposit rails so you can choose the venue that fits your jurisdiction and trade size.

Resolution & payout

Settlement is the biggest difference between the four platforms: Polymarket on-chain in USDC (instant), Kalshi USD via CFTC (T+1), Betfair and Smarkets in local currency via bank withdrawal (T+1 to T+3). On-chain settlement clears in minutes — the fastest payout path of the four.

FAQ

Polymarket vs Kalshi — which is better?

Depends on your location. Kalshi is CFTC-regulated, US-only with full KYC. Polymarket is global, on-chain, no KYC up to $1,500. Polymarket has ~10x higher liquidity but higher regulatory risk.

What does Polymarket cost vs Kalshi?

Polymarket: 0% fees, only Polygon network costs (~$0.01/trade). Kalshi: up to 7% per trade plus spread. For high-frequency traders, Polymarket is dramatically cheaper.

Is Betfair a Polymarket alternative?

Only partially. Betfair Exchange is UK-focused with a sports-betting emphasis; they have politics markets but with thinner liquidity than Polymarket. Settlement in GBP/EUR, 2-5% commission on winnings.

What about Smarkets as an alternative?

Smarkets is a UK betting exchange with a lower default commission (2%) than Betfair. Liquidity on political markets is below Polymarket, comparable to Kalshi. Geo-blocked in many jurisdictions.

Are all these platforms regulated?

No. Kalshi is CFTC-regulated (US). Betfair and Smarkets are UK Gambling Commission licensed. Polymarket operates without explicit regulation — a different risk profile than a regulated sportsbook.