Highest temperature in Seattle on July 23?

Platform comparison

Market context

Seattle-Tacoma International Airport’s highest temperature on 23 July will settle this market, so the key question is whether the day stays near a typical Seattle July high or pushes into an unusual warm spell. July in Seattle is normally around 75°F for daytime highs, with comparatively dry conditions and cooler evenings, which means the base rate favours a moderate maximum rather than an extreme print.[1]

That helps explain why a current crowd-implied probability of 0% YES is best read as a pricing artefact rather than a literal forecast of impossibility. Seattle has shown it can still produce mid-80s highs during July warm-ups, and recent regional heat coverage has highlighted how quickly the city can move from seasonal conditions to elevated temperatures when high pressure and inland flow align.[4] For a platform comparison, Polymarket and Kalshi typically present event probability directly, while Betfair and Smarkets are more often read through decimal prices and exchange liquidity, so the same view on the weather can look differently “cheap” or “expensive” depending on fees and the way each venue displays odds.

Traders should watch the National Weather Service and airport-specific temperature traces for any late-developing ridge, offshore flow, or marine-layer break that could lift the afternoon high at Sea-Tac above the usual July band.[2] Because the market resolves to the highest recorded airport temperature for the whole day, the decisive catalyst is not the morning forecast alone but the timing of the warmest window relative to cloud cover and sea-breeze penetration, with final settlement tied to the Wunderground history for Seattle-Tacoma International Airport.[2]

Sources: 1 · 2 · 3 · 4

Methodology

This page compares Highest temperature in Seattle on July 23? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. The live probability is the Polymarket mid; the comparison columns summarise each venue's fee structure, KYC, settlement currency and payment rails. Every CTA routes to Kalshi Alternative, which mirrors the Polymarket order book at 0% fees.

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.

Which platform has the deepest liquidity?

Polymarket — by a wide margin. Top markets reach $50-500M volume, Kalshi ~$200M cumulative, Betfair similar. Deeper liquidity means your trade moves the quote less.

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.

Which platform is accessible globally?

Polymarket is geo-blocked in the US/UK/EU. Kalshi is US-only. Betfair and Smarkets are UK-restricted. Kalshi Alternative has a different geo footprint and routes to Polymarket's order book at 0% fees.