Highest temperature in NYC on August 9?

Platform comparison

Market context

Polymarket is pricing the **90–91°F** band as the likely outcome for this LaGuardia-based temperature contract, with the market showing **0%** for YES at present on your provided crowd-implied figure. That matters because settlement is tied to the **highest reading in Weather Underground’s Daily Observations table** for KLGA, not the broader “Day High & Low” summary, so traders are effectively handicapping the exact published hourly maximum that appears before the observation window closes.

The current setup is best read against a warm August pattern rather than a one-off spike. Polymarket’s own market page says recent forecast guidance had pointed New York City towards a daily high near **90°F**, which explains why the 90–91°F and 92–93°F bins have carried most of the attention, while the reported latest observation from WeatherSpark for KLGA on 9 August showed **88.0°F** in the afternoon with a **6-hour high of 89.1°F**.[1][2] That kind of close-to-threshold outcome is exactly where these range markets can move sharply if the final observation ticks up or down by just a degree.

For traders, the key catalysts are the **next Weather Underground updates** and whether LaGuardia posts a late-day maximum before the daily file is locked for settlement, since Polymarket says revisions count only until the first datapoint for the following date appears.[2] The contract is a standard on-chain Polymarket position settled in **USDC on Polygon** through conditional-token mechanics, so the practical question is not the forecast headline but which temperature bin the final station observation lands in once Wunderground’s KLGA table stops updating.[2]

Sources: 1 · 2 · 3 · 4 · 5

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

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.

UK Frequently Asked Questions

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.

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%.