Highest temperature in San Francisco on August 13?

Platform comparison

Market context

San Francisco's maximum temperature on 13 August 2026 will be recorded at the airport weather station and resolved against historical temperature bands. The crowd currently assigns zero probability to any outcome, suggesting either incomplete market formation or an expectation that August temperatures in San Francisco cluster predictably within established ranges.

August in San Francisco typically produces highs between 65–75°F, with the airport station—situated near the coast—recording some of the coolest readings in the Bay Area. Historical data from the past two decades shows that temperatures exceeding 80°F on this date are rare, occurring perhaps once per decade. The 0% implied probability across all ranges indicates traders expect the actual high to fall within a baseline band that the market hasn't yet properly priced. This suggests either the favourite range hasn't been clearly identified in the market interface, or consensus is so tight that alternative outcomes appear negligible.

Traders should monitor early-August weather patterns and any heat dome forecasts from the National Weather Service in the weeks preceding settlement. Pacific high-pressure systems and marine layer strength will determine whether coastal cooling dominates or inland heat pushes temperatures higher. The resolution source—Weather Underground's Daily Observations table at SFO rather than the Day High & Low summary—creates a technical dependency worth confirming; discrepancies between the two sources have historically been minor but material for edge-finding traders. Settlement closes at 12:00 UTC on 13 August, meaning the final observation window is narrow.

Methodology

We track Highest temperature in San Francisco on August 13? 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

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

UK Frequently Asked Questions

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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.

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%.