Highest temperature in Chicago on August 9?

Platform comparison

Market context

Chicago’s temperature on 9 August will be decided by the actual **daily maximum at O’Hare** in Weather Underground’s Daily Observations table, not the summary box. That matters because the market can resolve on a different bin if the table is revised before the next day’s first observation appears, and the current crowd price of **0% YES** looks inconsistent with the recent Chicago setup, where AccuWeather showed an 87°F high for 9 August and the National Weather Service’s Chicago-O’Hare normal high for that date is about 83°F.[1][2]

For comparison, Polymarket expresses this market as an outcome-bin probability, while Kalshi and Smarkets typically present price as a dollar or decimal-style contract value, and Betfair’s exchange format adds commission on winnings rather than embedding the fee in the quote. On the available listings, Polymarket’s own market page had already moved to **84–85°F at 100%** for 9 August, which shows how quickly these temperature books can drift from a near-zero screenshot to a near-certain bin once late-day observations are locked in.[3]

The main catalysts are the evening and overnight observation updates, plus whether any post-midnight correction appears before the first 10 August datapoint. Chicago’s weather service forecast page showed cool overnight conditions and a 70°F reading around 2:53 am CDT, which limits the chance of a late spike unless an afternoon warm-up arrives earlier than expected.[6] Traders should also watch O’Hare versus Midway updates, because the market resolves from the O’Hare station only, and some books are gated differently: Robinhood’s prediction markets are generally tighter on KYC and US access, while Betfair and Smarkets use exchange-style access and fee structures that can make small temperature bins price differently from Polymarket’s crowd-implied probabilities.[5][6]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in Chicago on August 9? 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

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.

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. Robinhood Prediction Markets 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. Robinhood Prediction Markets 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.