Highest temperature in San Francisco on July 13?

Platform comparison

Market context

San Francisco International Airport will record its peak temperature for 13 July 2026, with the market currently pricing a 7% chance that the highest reading exceeds the upper threshold of the most likely range. Historical data shows July highs in the city typically hover around 70°F, rarely surpassing 79°F, though extreme heat waves have pushed airport readings to 87°F in recent years [2][3]. The current 7% implied probability for the YES outcome contrasts sharply with Polymarket’s frontrunner outcome of 78–79°F at 50%, suggesting divergent interpretations of heatwave likelihood across platforms [1].

Traders should monitor the National Weather Service’s 72-hour forecast for the Bay Area, as a marine layer breakdown or offshore flow could trigger rapid temperature spikes. Recent heat records in the region, including 98°F at SFO during a 2013 wave, underscore the volatility of summer microclimates [3]. On platform mechanics, Kalshi and Betfair express this as decimal odds (roughly 13.3) rather than implied probability, while Smarkets applies a lower fee structure but requires stricter KYC verification than Polymarket’s global access. These structural differences often create temporary pricing inefficiencies on weather binaries like this one.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in San Francisco on July 13? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live mid is the canonical probability; the side-by-side columns benchmark fees, KYC, settlement currency and deposit rails so you can choose the venue that fits your jurisdiction and trade size.

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

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.

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.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Polymarket 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.