Highest temperature in San Francisco on August 10?

Platform comparison

Market context

San Francisco International Airport’s top reading on 10 August will be the figure that matters for settlement, and the contract explicitly keys off the Weather Underground **Daily Observations** table rather than any headline “day high” widget. Early observations already showed a cool start, with the National Weather Service reporting San Francisco Downtown at 59°F with high humidity just after 01:43 UTC, while historical airport data for 10 August points to a normal maximum around the low 70s Fahrenheit and a record high in the upper 80s, so the market is really about whether the airport nudges into a typical summer afternoon range or stays held down by marine air.[13][6]

For context, recent and comparable August readings at the airport have often clustered in the high 60s to low 70s, with Weather Underground’s history page showing 71°F around early afternoon on 10 August in the 2026 archive and the National Weather Service climatological report giving a previous maximum of 71°F for yesterday and a daily normal maximum of 73°F for 10 August. That makes a 0% YES price on a higher band especially interesting for a programmatic trader: the market is effectively pricing an outcome that would require a clear break above the recent run-rate, not just a routine afternoon warm-up.[1][6]

Catalysts to watch are operational rather than event-driven: the exact timestamp of the warmest hourly observation in the Daily Observations table, possible late-afternoon mixing or coastal fog pushing the peak earlier, and any refresh lag or discrepancy between Weather Underground’s summary and table outputs. A bot or conditional-order setup should poll the table directly, compare successive temperature updates, and be ready to mark the market when the final pre-settlement peak is locked in, because the resolution source is the observed airport table entry, not forecast models or summary tiles.[2][9]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in San Francisco on August 10? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Polymarket Review UK, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

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

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

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%.