Highest temperature in San Francisco on August 5?

Platform comparison

Market context

San Francisco’s coastal weather setup has shifted towards a warmer inland-leaning pattern, but the airport itself still sits under a marine influence that often caps the day’s peak well below the Bay Area’s hotter interior locations. Recent Bay Area coverage says a broader California heat wave was starting around this period, with the National Weather Service flagging elevated heat risk across inland parts of Northern California, while also noting that San Francisco and Oakland were unlikely to see a long-duration heat wave because the marine layer remained in place.[16]

That context helps explain why the market is clustered around the upper 60s to low 70s rather than the 80s and 90s seen inland. Polymarket’s live book showed the strongest crowd support in the 70–71°F and 72–73°F bands, both near 49%, with materially lower pricing only once the range moves towards the mid-80s and above.[1] For a San Francisco International Airport reading, that is consistent with August climatology: the city’s late-summer highs are generally mild compared with the rest of the Bay Area, and airport-observed temperatures can lag warmer inland bursts when the sea breeze holds.[2][11][18]

For traders, the key watchpoints are the day’s realised marine-layer break-up, any late-morning coastal clearing, and whether inland heat advection pushes far enough west to lift SFO above the mid-70s. The settlement source is Weather Underground’s daily history page for KSFO, so the only number that matters is the recorded daily maximum at the airport, not a citywide forecast or a nearby station.[3][15] A fresh terminal forecast update from the National Weather Service or a local broadcast note on the Bay Area heat plume would be the most relevant catalyst if it showed stronger or weaker onshore flow than expected.[16][18]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Prediction Today, which mirrors the Polymarket order book directly.

Resolution & payout

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On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

UK Frequently Asked Questions

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Prediction Today. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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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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Do I pay tax on prediction market profits in the UK?

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