Highest temperature in Seattle on August 4?

Platform comparison

Market context

Seattle’s temperature on 4 August will be judged by the highest reading at Seattle-Tacoma International Airport, not by an average citywide high, so late-afternoon peaks and brief warm spikes matter more than the daytime forecast headline. The market is currently pricing a 0% YES on the listed resolution framing, which is clearly detached from the live temperature bands on major books: Polymarket’s own event page shows the strongest cluster around 84–85°F, with 82–83°F and 86–87°F also active, indicating the crowd expects a warm but still fairly ordinary summer peak rather than a cold-day outcome.[2]

The historical frame for this kind of contract is simple: Seattle in August usually sits in the upper 70s to low 80s, with AccuWeather’s monthly guide showing 81°F / 62°F for 4 August and WeatherSpark describing August as one of the city’s warmer months, though still moderated by marine influence.[1][9] That makes mid-80s plausible when offshore ridging or a warm inland flow develops, but it also leaves plenty of room for a lower peak if the sea breeze arrives early. On Polymarket, prices are displayed as direct implied probabilities, whereas Kalshi and Betfair-style books can present the same view as decimal odds or exchange prices, which changes the visual feel of the market even when the underlying expectation is similar; fee drag and KYC access also differ materially across venues, with exchange-style products often having wider eligibility but more variable execution costs.

The main catalysts are the short-range weather model runs, National Weather Service forecasts, and any forecast updates that shift the strength or timing of the marine layer. Polymarket’s market page itself flags that revisions to temperatures within the settlement window are considered until the first datapoint for the following day is published, so traders should watch the final hourly observations around the airport rather than the afternoon headline high alone.[2] If you are comparing platforms, the practical edge is less about the story than the plumbing: Polymarket and Kalshi surface probabilities directly, while Betfair and Smarkets typically require reading the spread after commission, and KYC availability may determine whether a trader can access the contract at all.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in Seattle on August 4? 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

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

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. Polymarket Alternative has a different geo footprint and routes to Polymarket's order book at 0% fees.

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.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Polymarket Alternative offers a fiat on-ramp via Klarna or SOFORT (DE/AT/CH) and converts internally to USDC for the Polymarket order book. T+1 processing.