Pronóstico: Highest temperature in Chicago on August 9?

Platform comparison

Market context

Polymarket is pricing this Chicago O’Hare daily-high contract at **0% Yes**, so the market is effectively saying the named temperature band is already locked in with no meaningful residual uncertainty. On Polymarket, traders buy and sell conditional tokens settled in **USDC** on **Polygon**, and the winning band pays out $1 per share once the market resolves from the Weather Underground daily observations for Chicago O’Hare, not the summary “Day High & Low” figure.

The historical frame is fairly ordinary for early August in Chicago: the National Weather Service lists an **83°F** normal maximum for 9 August at O’Hare, with a **97°F** record for that date, which puts the event inside a well-worn summer range rather than a rare extreme.[2][13][14] Weather Underground’s record-style daily tables and other Chicago climate summaries also point to mid-80s seasonal highs, and recent comparable August readings have clustered near that level rather than at the top end of the record distribution.[1][6][12]

For traders, the main catalysts are the final observation sequence and any late revisions in Weather Underground’s daily history, because the contract resolves only after the first datapoint for the following date appears and the relevant daily observations are complete.[3] In practical terms, the watchlist is the O’Hare station feed, the timing of the first post-midnight UTC updates, and any rapid weather changes that could alter the late-afternoon maximum; local forecasts on 9 August pointed to hot, humid conditions with thunderstorms possible later in the day, which can cap the realised high if cloud cover or convection arrives early.[5][11]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Pronóstico: Highest temperature in Chicago on August 9? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Polymarket Qué Es, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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 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.