Highest temperature in San Francisco on August 5?

Platform comparison

Market context

The outcome will be set by the highest reading at San Francisco International Airport on 5 August 2026, as reported by Weather Underground, so the key question is the day’s actual airport high rather than the citywide forecast. With the settlement source tied to a single station, small microclimate differences across the Bay Area do not matter unless they show up in the KSFO observations.

The market is currently pricing a 0% YES chance, but the reference frame is a coastal August climate where highs are often restrained by marine air. For comparison, Polymarket’s live book on the same event showed most interest clustered around the low-70s Fahrenheit bands, with 72–73°F leading at 51% and 74–75°F next at 21%, which implies traders are leaning towards a modest airport high rather than an extreme heat print.[1] San Francisco’s August averages also sit around the low 70s, with AccuWeather’s monthly page showing roughly 70°F as a typical daytime high.[2]

The main catalyst is the strength and timing of any inland heat surge, because coastal onshore flow can cap KSFO temperatures even when the wider region is warm. The National Weather Service’s climate discussion for the San Francisco airport notes the station’s daily highs and gives context for how quickly marine influence can suppress or lift readings, while a San Francisco Chronicle weather report said the Bay Area could see temperatures spike from 5–8 August as a broader California heat wave builds.[15][16] For crypto traders, this is a short-duration, oracle-style settlement on USDC rails, so the on-chain angle is mostly about liquidity, spreads, and any late moves in BTC or ETH that affect overall risk appetite rather than the weather contract itself.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reads Highest temperature in San Francisco on August 5? on-chain. Polymarket's quote comes directly from the Polygon order book — the only comparable venue with on-chain settlement. Kalshi (USD, off-chain), Betfair (GBP/EUR, off-chain) and Manifold (play-money) are listed alongside for venue context. Every CTA routes to BTC Prediction, which mirrors the Polymarket order book directly.

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.

How does UMA secure the resolution?

The UMA Optimistic Oracle uses a bond system: a proposer posts a bond, a two-hour challenge window opens. On dispute the losing side forfeits the bond — financial incentive for honest resolution.

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%.