Highest temperature in San Francisco on July 13?

Platform comparison

Market context

San Francisco International Airport is expected to record its peak daily temperature for 13 July 2026, with the market currently pricing a specific high-temperature outcome at just 5% implied probability. This low probability reflects the city’s maritime climate, where July highs typically hover around 70°F, rarely exceeding 79°F even during warm spells [1]. Historical data shows that while extreme heat waves have pushed KSFO to 87°F in 2013, such events are outliers rather than norms, making a temperature spike into the upper range statistically improbable without a confirmed atmospheric anomaly [2].

Traders should monitor the National Weather Service’s forecast for the Bay Area, particularly any updates on ridge formation or marine layer breakdown, which are the primary catalysts for sudden temperature rises in coastal California [3]. Recent heat waves in the region have been driven by inland pressure systems pushing hot air toward the coast, but July 13 has not historically featured triple-digit readings at the airport, with the all-time record for the date sitting at 87°F [2]. The divergence between platforms is notable here: Polymarket displays this as 5% implied probability, whereas Kalshi would likely list decimal odds of 20.0, and fee structures vary significantly, with Smarkets offering lower commission rates for UK-based traders compared to Kalshi’s KYC-heavy model.

Current conditions show a low of 54.3°F on 11 July, suggesting stable marine influence rather than an impending heat event [6]. With settlement ending at 12:00 UTC on 13 July, the market resolves strictly on Wunderground’s recorded high for KSFO, meaning even a brief spike above 79°F would trigger a YES outcome, though historical norms make this unlikely [9]. Platform comparisons reveal that Betfair’s liquidity may be thinner on such niche weather contracts compared to Polymarket’s crypto-native user base, while Kalshi’s regulatory compliance adds friction for international participants seeking similar exposure.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest temperature in San Francisco on July 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.

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 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.