Highest temperature in San Francisco on August 5?

Platform comparison

Market context

San Francisco International Airport’s daytime high on 5 August is the settlement driver, and the current market split points to a fairly narrow summer range rather than an outlier heat event. Polymarket’s top band is **72-73°F at 51%**, with **74-75°F at 21%** and **70-71°F at 19%**; by contrast, Robinhood’s related contract is centred lower, around **71°F** at the time of capture, while Kalshi’s nearby daily-high market for 5 August showed most probability clustered in the mid-70s on the preceding day. [1][8][18]

That distribution fits the airport’s August climate profile, where San Francisco typically posts mild afternoons and only occasionally reaches the upper 70s or beyond. AccuWeather’s August outlook for the city shows daily highs around the high 60s to about 70°F, and WeatherSpark’s August climate normals likewise place the month in a cool coastal pattern rather than a sustained heat regime. [2][9] A useful comparator is the midweek setup already seen in the city, where forecasts called for partly cloudy conditions and temperatures in the low-to-mid 60s, underscoring how quickly marine influence can cap the airport high even when inland Bay Area stations run much hotter. [3][10]

For traders, the key catalyst is whether the marine layer erodes enough for the airport to get a clean afternoon warm-up, or whether coastal fog and onshore flow keep the high anchored in the low 70s. The San Francisco Chronicle reported a broader California heat wave building from Friday, with NWS heat-risk messaging extending into parts of the Bay Area from 5-8 August, but those warnings are more relevant to inland cities than to KSFO itself. [13] On a cross-platform read, the crowd-implied probability is consistent with a modestly warm airport reading, while the sportsbook-style lines appear to lean slightly lower; the main divergence is not on the direction of risk, but on how much weight to give a late-day push into the mid-70s.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in San Francisco on August 5? 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

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 Best Prediction Markets UK. 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.

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.

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.

What are the best prediction markets for UK traders in 2026?

For UKGC-regulated markets: Betfair Exchange (sports, politics) and Smarkets (sports, politics, lower commission than Betfair). For broader global event prediction: Polymarket (deepest liquidity, 0% fee, USDC settlement). For US-regulated option: Kalshi (USD, limited UK payment options). Most serious UK traders use a combination of Betfair for regulated sports and Polymarket for broader markets.