Highest temperature in San Francisco on August 5?

Platform comparison

Market context

The event is the **highest temperature recorded at San Francisco International Airport** on 5 August, and the key point is that the settlement source is a single station reading rather than a citywide average. In practice, that means the market is usually driven by the forecast for SFO’s immediate microclimate, where maritime influence often keeps afternoon highs tightly clustered and makes the exact bucket more sensitive to small forecast shifts than in inland California markets.[3][16][17]

The current 0% crowd-implied YES price is best read as a platform artefact rather than a literal impossibility, because weather markets on Polymarket often move in very fine increments and can be quoted as implied probabilities, while Kalshi and Robinhood-style displays typically show contract prices in cents that map to a payout structure. For comparison, Polymarket’s current distribution shows the field concentrated around the upper 60s to low 70s Fahrenheit, with 70–71°F and 72–73°F both shown at 49% on the market page, which suggests traders see a narrow band as most likely rather than a broad temperature spike.[2][6]

For catalysts, traders should watch the National Weather Service SFO climate products, local forecast updates, and any Bay Area heatwave coverage, because even modest changes in the marine layer, onshore flow, or inland warming can shift the high by a degree or two. That matters more on venues with different fee and access models: Polymarket and Betfair-style exchanges tend to price continuous probability changes, while Kalshi and Smarkets usually express the same information through cents or decimal odds and may differ on KYC availability by jurisdiction, so cross-platform comparisons can look divergent even when the underlying forecast is the same.[16][17][18]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in San Francisco on August 5? 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

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

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.