Highest temperature in Miami on August 5?

Platform comparison

Market context

Miami’s airport high on 5 August is a straightforward weather print, but the contract settles on the **highest** observed temperature at the Miami Intl Airport Station, not a forecast or citywide average. That makes intraday heat spikes, cloud cover timing and any thunderstorm-driven cooling more relevant than the morning low, and the fact that settlement uses Weather Underground’s KMIA history means the final value is fixed only once the day’s data are complete.[8]

The current 0% YES crowd price looks far too low against the available forecasts and Miami’s summer climatology. AccuWeather showed a daily high of **89°F** for 5 August and **89°F** again for 6 August, while CBS Miami was forecasting around **90°F** with hot, humid conditions on 5 August.[1][2] That sits squarely in the kind of mid-to-upper 80s and low-90s August range implied by Miami’s normal heat profile, so the market appears to be pricing an outcome that would require a materially cooler-than-expected day or a misread of the settlement mechanics.[1][2][13]

For traders, the key catalysts are the short-range forecast updates, the timing of afternoon showers and whether the airport station records a brief peak before convection knocks temperatures back. NOAA/NWS products for Miami remain the main public reference point for near-term heat risk, while the market’s own resolution window means any late-day revision to the Weather Underground record can matter only until the next day’s first datapoint is published.[7][8][11] In crypto terms, this is a simple USDC-settled event with no direct BTC or ETH linkage; the only macro spillover is via general risk appetite, which can affect liquidity and how tightly the market tracks the forecast rather than the weather 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 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.

Can I use Bitcoin directly?

No, Polymarket operates exclusively in USDC on Polygon. You can bridge BTC to USDC via an exchange or bridge service and deposit on Polygon — typically 10-30 minutes processing time.

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%.