Highest temperature in NYC on August 8?

Platform comparison

Market context

The key event is the highest Fahrenheit reading at LaGuardia Airport on 8 August, using Weather Underground’s daily observations table as the settlement source. By the time this market closed, the station had already posted an afternoon peak of 89.1°F in related live weather reporting, which is consistent with a late-summer NYC heat regime but just below the 90–91°F band the crowd had been pricing most aggressively.[2][3]

The 0% YES quote looks anchored to a near-certain read on the observed daily high rather than a live forecast. Recent New York climate reports show a 91°F maximum at Central Park on 8 August 2025 and a 100°F daily tie during the early-July 2026 heat wave, so traders have recently seen both moderate and extreme outcomes in the city’s summer temperature distribution.[4][7] August norms are still much lower, with long-run daytime highs around the upper 80s Fahrenheit, which makes a low-90s outcome notable but not unusual enough to be implausible.[8]

What matters now is not weather risk but data finality: the contract resolves only after Weather Underground publishes the next day’s first observation, and any late revision before that point can still alter the final print.[10] On the crypto side, the payoff is USDC-settled on-chain, so the market can reprice quickly if related risk appetite shifts across BTC and ETH; when funding stays elevated or spot flows are strong, small satellite markets often move more on liquidity conditions than on fresh weather information. The practical catalyst is therefore the final Wunderground update, not another forecast cycle.[10]

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

Why USDC and not ETH or USDT?

USDC is the Polygon standard — audited reserves (Circle, monthly attestation), deepest order book, low gas costs. ETH volatility would distort probability quotes; USDT has thinner Polygon liquidity than USDC.

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%.