Highest temperature in San Francisco on August 10?

Platform comparison

Market context

Polymarket is pricing this San Francisco airport temperature contract at **0% YES** on a USDC market that settles through Polygon conditional tokens, so the implied view is that a reading in the relevant Fahrenheit band is treated as effectively impossible. The real-world event is a single-day maximum at San Francisco International Airport, and the resolution rule matters: Weather Underground’s **Daily Observations** table is primary, not the broader “Day High & Low” summary, so traders are really exposed to the station’s recorded intraday peak rather than a headline number.[8]

Historically, San Francisco’s August highs usually sit in the low 70s Fahrenheit, with recent early-August readings around the upper 60s to mid-70s and a climatological August average high near 70.5°F.[2][6] Weather Underground’s SFO history for the same date shows a reported high of 59°F at midnight in the sample available, while the NOAA daily climate report for the airport shows yesterday’s maximum at 71°F, underlining how coastal marine conditions can keep the station close to the seasonal norm rather than producing extreme heat.[8][3] For a market already at 0%, the historical frame mostly says that only an unusually warm offshore or downslope setup would move the needle far above the usual range.[10]

A trader watching this market should track the airport’s hourly observations, marine layer strength, and any late-summer heat signal in the Bay Area forecast cycle, because the settlement depends on the maximum actually logged before the window closes.[11][4] The key dependency is not city-wide weather but the specific SFO station feed on Weather Underground, where brief midday spikes can matter more than the overall day profile.[8] Since the market settles in USDC through on-chain conditional tokens, a late shift in observations can reprice the contract quickly if the airport warms faster than surrounding sites, even when the broader San Francisco forecast looks modest.[8][11]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in San Francisco on August 10? 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

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.

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%.