Highest temperature in Chicago on August 9?

Platform comparison

Market context

The settlement will hinge on the **highest observed temperature** at Chicago O’Hare on 9 August, as recorded in Weather Underground’s Daily Observations table, not the headline day-high figure. For a programmatic workflow, the cleanest approach is to poll the KORD daily history page after the observation day closes and wait for the first datapoint from 10 August UTC/local publication to appear, because the contract only treats later revisions as valid up to that point.[1][9]

The current **0% YES** price is hard to reconcile with the surrounding temperature backdrop. Chicago’s August normal high is about **83°F** at O’Hare, while the record for 9 August is **97°F**; that leaves a wide but not extreme band where outcomes can cluster around the low-to-mid 80s in a typical summer setup.[11][13] Recent official reporting also shows O’Hare had an **84°F** daily maximum on 9 August in the climatological daily report, which is the sort of value that often anchors these bins when traders are pricing a narrow outcome range.[3]

For a trader using tooling, the main catalysts are late-afternoon heating, cloud cover, storm timing, and whether any airport observation is updated after initial publication. The practical dependency chain is the O’Hare station feed, then the Weather Underground Daily Observations page, then the contract’s bin mapping; that means bots or conditional orders should watch for the final maximum rather than the first daily high shown in a summary tile.[1][9] Local forecast products for Chicago on 9 August showed highs around the low-to-mid 80s, which is relevant only insofar as it frames whether the realised maximum could still land in an adjacent temperature band.[2][6]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Polymarket Bot UK, which mirrors the Polymarket order book directly.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

UK Frequently Asked Questions

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.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.