Highest temperature in San Francisco on August 13?

Platform comparison

Market context

San Francisco's weather on 13 August 2026 will determine which temperature bracket captures the day's peak reading at the airport station. The market currently prices all outcomes at 0%, reflecting either a technical settlement issue or genuine uncertainty about which range will resolve true. Resolution depends on Weather Underground's Daily Observations table rather than summary figures, a distinction that matters when automated systems and manual readings diverge—a known source of discrepancy in historical weather data.

August temperatures at San Francisco International Airport typically peak between 75°F and 85°F, though the airport's coastal location moderates extremes compared to inland Bay Area stations. Historical August highs rarely exceed 90°F at SFO; the airport's 30-year average high for mid-August sits around 78°F. Comparable August 13th readings from recent years show consistency within the 70–82°F range, suggesting the market's current pricing may reflect genuine ambiguity about which specific bracket will contain the actual high rather than doubt about whether a reading will occur.

Traders monitoring this contract should track National Weather Service forecasts as mid-August 2026 approaches, particularly any heat advisories or unusual atmospheric patterns that could push temperatures toward seasonal extremes. Pacific high-pressure systems and marine layer strength typically govern Bay Area August conditions; any shift in these patterns would be visible in extended forecasts 10–14 days prior to settlement. The precise resolution mechanism—relying on Weather Underground's Daily Observations table at a specific station—means traders should verify historical consistency at that exact data source rather than relying on broader regional climate patterns.

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 PolyGram, which mirrors the Polymarket order book directly.

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

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 PolyGram. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

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%.