Highest temperature in San Francisco on August 5?

Platform comparison

Market context

San Francisco International Airport’s highest temperature on 5 August is the settlement point, and the market is really a bet on whether the day peaks in the mid-70s or stays closer to the low 70s. Polymarket’s current book has the 72–73°F bin leading at 51% and 74–75°F next at 25%, while Kalshi’s parallel contract is organised as a different payoff ladder, with prices shown in decimal-style contract terms rather than Polymarket’s headline implied probabilities. That makes cross-platform comparison useful but not mechanical: the same weather view can be expressed at different strike bands, with different fees, and with different access frictions depending on KYC and jurisdiction.

Historically, San Francisco’s August highs cluster near the low 70s, so a market anchored around 72–75°F is not aggressive by local standards. Polymarket’s own framing notes a long-term August average high of about 70°F, while AccuWeather’s monthly outlook also points to a typical August high around 70°F and low around 57°F. Against that backdrop, a 0% YES reading is more a function of the market’s current price map than an assertion that the airport cannot touch the relevant band; on venue conventions, the last published Wunderground datapoint before the next day’s first reading is what matters for settlement.

The main catalyst is the actual daytime weather evolution at KSFO, especially any marine-layer break, inland heat spill-over, or late-afternoon warming that could push the maximum one bracket higher. A recent Bay Area forecast note from the San Francisco Chronicle said temperatures were likely to spike from 5–8 August, which is the kind of regional setup traders watch for when a coastal airport sits near a band boundary. For Polymarket traders, the practical focus is the live probability distribution; on Kalshi or Betfair the same move may show up as tighter bid-offer changes or different decimal odds, while Smarkets users will also need to account for venue-specific fees and account verification before they can react.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest temperature in San Francisco on August 5? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. The live probability is the Polymarket mid; the comparison columns summarise each venue's fee structure, KYC, settlement currency and payment rails. Every CTA routes to Polymarket Alternative, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Polymarket vs Kalshi — which is better?

Depends on your location. Kalshi is CFTC-regulated, US-only with full KYC. Polymarket is global, on-chain, no KYC up to $1,500. Polymarket has ~10x higher liquidity but higher regulatory risk.

Which platform has the deepest liquidity?

Polymarket — by a wide margin. Top markets reach $50-500M volume, Kalshi ~$200M cumulative, Betfair similar. Deeper liquidity means your trade moves the quote less.

Is Betfair a Polymarket alternative?

Only partially. Betfair Exchange is UK-focused with a sports-betting emphasis; they have politics markets but with thinner liquidity than Polymarket. Settlement in GBP/EUR, 2-5% commission on winnings.

What about Smarkets as an alternative?

Smarkets is a UK betting exchange with a lower default commission (2%) than Betfair. Liquidity on political markets is below Polymarket, comparable to Kalshi. Geo-blocked in many jurisdictions.

Which platform is accessible globally?

Polymarket is geo-blocked in the US/UK/EU. Kalshi is US-only. Betfair and Smarkets are UK-restricted. Polymarket Alternative has a different geo footprint and routes to Polymarket's order book at 0% fees.