Highest temperature in San Francisco on August 5?

Platform comparison

Market context

San Francisco International Airport is the settlement point, so the real-world question is whether the day’s **highest** reading at KSFO clears the low-70s band that the market has centred on. The crowd-implied 0% YES in the 76–77°F bin leaves the favourite clustered lower down, with the consensus still around a mild summer maximum rather than a genuine hot-spell print.[1][16]

Historically, August highs at San Francisco are usually modest by inland California standards, with long-run August normals around 70°F and only limited upside when the marine layer holds.[2][13] That is why the market’s pricing leans to the low-to-mid 70s: traders are effectively treating 72–73°F as the favourite and 74–75°F as the main underdog/value pocket, while anything above 75°F remains a contrarian long shot unless conditions break cleaner than forecast.[1][18]

The main catalysts are the local forecast evolution, coastal stratus timing, and any heat-wave spillover reaching the Bay Area. Recent reporting flagged a broader California heat event beginning around this window, but also noted that San Francisco is less likely than inland areas to get a sustained surge because the marine layer can cap daytime highs, so late-breaking sunshine or offshore flow is the key dependency for upside tails.[17] Because the market settles on the maximum at KSFO for the full day, traders should watch not just the midday forecast but whether morning fog burns off early enough to allow a brief top-end move.[1][16]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in San Francisco on August 5? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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

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How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

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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%.