Highest temperature in Chicago on August 9?

Platform comparison

Market context

Chicago’s outcome depends on the highest **observed** temperature at O’Hare, not the forecast headline, and the market has already moved to a 0%/near-0% view on the low end because the late-summer Chicago climatology is usually well above the coolest bands. NOAA’s August normal for Chicago on 9 August is 83.3°F, while Weather Underground’s historical page for Chicago shows a typical high around the mid-80s, so the contract is really about whether the day lands a degree or two either side of normal rather than a rare cool spell.[3][16]

Comparable cases suggest the tail risk is a true cold intrusion, but that is uncommon in early August. Chicago’s record history for 9 August includes highs as warm as 97°F and a long-run average high around 83°F, which means settlement usually sits in the 80s unless a strong front arrives or cloud/rain suppresses the afternoon peak.[6][7] For an on-chain market settled in USDC, that makes the crowd-implied probability sensitive less to long-range outlooks than to the actual station observations that feed the final Weather Underground table.

The practical catalysts are the afternoon evolution of the weather map, airport-specific obs, and any last-minute revisions before the first reading for 10 August is published, because the contract uses the Daily Observations table as the primary source.[1][17] Traders usually watch whether a weak ridge holds over the Upper Midwest or a front slips far enough south to cap highs; recent guidance cited by Polymarket pointed to near-normal temperatures and no major heat advection, which supports the market’s concentration in the mid-80s rather than a breakout into the 90s.[1] If broader crypto conditions matter, BTC and ETH basis, funding, or large spot flows can influence liquidity and risk appetite, but they do not change the weather settlement itself.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically this overview focuses on on-chain pricing: Polymarket's live mid comes from the Polygon conditional-token order book and settles automatically in USDC. The other three venues — Kalshi, Betfair, Manifold — sit alongside as off-chain reference points so you can see how the contract translates across regulatory and settlement regimes.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

UK Frequently Asked Questions

What are crypto prediction markets?

Crypto prediction markets are on-chain smart contracts where you buy YES or NO shares on a future crypto event (e.g. "BTC above $100k by year-end"). The market price between 0¢ and 100¢ is the implied probability.

What does a transaction cost on Polygon?

Polygon gas is typically under $0.01 per transaction. A full trade cycle (Approve + Order + Fill) totals around $0.03 — compared to $5-50 on Ethereum mainnet.

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%.