Highest temperature in San Francisco on August 13?

Platform comparison

Market context

San Francisco's peak temperature on 13 August 2026 will be recorded at the airport weather station and resolved against Weather Underground's Daily Observations table rather than its summary display—a distinction that matters when platforms diverge on data sourcing. The current 0% crowd probability suggests traders expect temperatures to fall outside whatever range this market's upper bound specifies, though the exact threshold bands vary across platforms. Polymarket and Kalshi structure such weather markets differently: Polymarket typically uses decimal odds with tighter spreads on niche outcomes, whilst Kalshi's binary framework and US-focused KYC requirements shape which traders can access this contract. Betfair and Smarkets offer broader geographic reach but handle weather resolution through different data hierarchies, making source specification critical here.

San Francisco's August climate is relatively stable, with historical highs clustering between 75–85°F at the airport. The National Weather Service's August 2025 forecast indicated no anomalous heat patterns developing into 2026, though El Niño or La Niña transitions could shift baseline expectations. Traders should monitor NOAA's seasonal outlooks released in July 2026 and any late-month heat advisories issued by the Bay Area National Weather Service office, which would signal departure from climatological norms. The resolution window closes at 12:00 UTC on the settlement date, meaning afternoon temperature spikes after that timestamp will not affect the outcome.

Methodology

This page compares Highest temperature in San Francisco on August 13? 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 Kalshi Alternative, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Settlement is the biggest difference between the four platforms: Polymarket on-chain in USDC (instant), Kalshi USD via CFTC (T+1), Betfair and Smarkets in local currency via bank withdrawal (T+1 to T+3). On-chain settlement clears in minutes — the fastest payout path of the four.

FAQ

What does Polymarket cost vs Kalshi?

Polymarket: 0% fees, only Polygon network costs (~$0.01/trade). Kalshi: up to 7% per trade plus spread. For high-frequency traders, Polymarket is dramatically cheaper.

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. Kalshi Alternative has a different geo footprint and routes to Polymarket's order book at 0% fees.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Kalshi Alternative offers a fiat on-ramp via Klarna or SOFORT (DE/AT/CH) and converts internally to USDC for the Polymarket order book. T+1 processing.