Highest temperature in NYC on August 11?

Platform comparison

Market context

New York City's maximum temperature on 11 August 2026 will be recorded at LaGuardia Airport's official weather station and resolved against the Daily Observations table on Weather Underground rather than the Day High & Low summary—a distinction that matters when automated systems pull data from different endpoints. The settlement window closes at midday UTC, meaning the full 24-hour observation period will be captured before resolution.

August temperatures at LaGuardia historically cluster between 78–88°F, with the airport's all-time August high of 102°F set in 1933. Recent Augusts have seen daily highs in the low-to-mid 80s, though heat domes occasionally push readings into the low 90s. The 0% crowd probability suggests traders are pricing in either a narrow range expectation or uncertainty about which temperature bracket will resolve. Comparable markets on specific daily temperature outcomes at major US airports typically show low liquidity until within 72 hours of settlement, when atmospheric models stabilise.

A trader automating this market would need to reconcile Weather Underground's API responses against their own weather data feeds—the Daily Observations table updates hourly and occasionally shows discrepancies with summary displays due to sensor recalibration or data reprocessing. The National Weather Service's Advanced Hydrologic Prediction Service publishes extended forecasts in early August; tracking the GFS and NAM models from mid-July onwards provides the earliest signal for whether a heat event is materialising. Any tropical system tracking towards the Northeast in early August would shift probability distributions materially, though August 11 typically falls outside Atlantic hurricane season's peak impact window.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Review UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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%.