Highest temperature in London on August 1?

Platform comparison

Market context

London’s peak temperature on 1 August will be set by the highest reading recorded at London City Airport Station, and the market resolves on the Celsius band containing that daily maximum. The Polymarket board is currently centred on **26°C**, with nearby bins at **25°C** and **27°C** carrying most of the remaining weight, which is consistent with a fairly tight late-summer forecast rather than a broad heatwave distribution.[1]

That shape fits the historical pattern for London in August, where daily highs are often in the low 20s Celsius but occasional warm spells push maxima into the mid-to-high 20s, especially under sunny, light-wind conditions.[5][10] Recent 2026 UK heat has already shown how quickly London can spike: Kew Gardens reached **26.6°C** and later **32.3°C** in separate readings this year, underlining that central and west London can warm sharply when continental air and strong sunshine line up.[7][14] On Polymarket, the quoted prices are direct implied probabilities; on Kalshi, the same view would usually be expressed as a cents price on a binary contract, while Betfair and Smarkets quote decimal odds and embed exchange commission rather than a built-in market spread.[1]

For traders, the main catalysts are the Met Office short-range forecast, any late-day cloud or sea-breeze effects, and the exact Wunderground station observation sequence used for settlement. Polymarket notes that revisions are counted only until the first datapoint for the following date is published, so late corrections after that point should not affect the outcome.[1] Platform access also matters: Polymarket is crypto-native with a wider global reach, while Kalshi is US-regulated and more KYC-bound, and Betfair/Smarkets depend on exchange-style liquidity and fees that can make a narrow temperature band less expensive or more expensive to express depending on market depth.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in London on August 1? 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.

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.

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.