Highest temperature in London on July 13?

Platform comparison

Market context

London City Airport is forecast to reach 27°C today, 13 July 2026, as sunny conditions and a moderate southerly breeze drive temperatures toward the month’s typical peak[1][6]. The market’s 1% YES probability on a specific high-temperature outcome appears misaligned with historical patterns, where July is London’s hottest month with an average high of 22°C (72°F) and frequent spikes above 30°C during heatwaves[1]. Record highs in London reached 40.2°C on 19 July 2022, while temperatures of 35°C or higher have now been recorded in May, June, and July in the same year for the first time in UK history[4][5]. Such precedents suggest that extreme heat is not anomalous, making the current crowd-implied probability unusually conservative compared to comparable cases.

Traders should monitor the Met Office’s hourly updates and Wunderground’s live station data for EGLC, as settlement hinges on the highest temperature recorded at London City Airport specifically[4]. Recent heatwave announcements from the UK government and Met Office highlight increased vigilance for temperatures exceeding 35°C across London, a catalyst that could shift implied probabilities if sustained[4]. On platform mechanics, Polymarket displays this event with 27°C as the frontrunner at 41–52% implied probability using decimal odds, whereas Kalshi, Betfair, and Smarkets typically quote decimal odds directly and apply different fee structures and KYC thresholds, creating divergence in how the same weather outcome is priced across books[2]. These structural differences mean traders comparing liquidity and execution costs must account for how each platform frames probability versus odds on identical weather events.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest temperature in London 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 UK, 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.

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

Are all these platforms regulated?

No. Kalshi is CFTC-regulated (US). Betfair and Smarkets are UK Gambling Commission licensed. Polymarket operates without explicit regulation — a different risk profile than a regulated sportsbook.