Highest temperature in London on July 12?

Platform comparison

Market context

London faces a critical heat check on 12 July 2026 as traders assess the likelihood of extreme temperatures at London City Airport. The settlement window closes at noon UTC, with the market currently implying a 0% probability for any specific outcome, suggesting a potential pricing error or extreme uncertainty in the current liquidity. Historical records for mid-July in London show a ceiling of 31.6°C at nearby Heathrow in 1983, while the absolute UK record reached 40.2°C in 2022, though such extremes are rare for this specific urban location [2][8]. The 2026 July forecast for London City Airport projects daily highs between 21°C and 31°C, providing a realistic baseline that contrasts sharply with the current zero-implied probability [1].

Traders should monitor real-time METAR data from EGLC and the Met Office’s seven-day forecast for London City Airport, which tracks temperature, wind, and UV levels closely [6]. A divergence exists between the 0% implied probability on this contract and the active Polymarket lines, where 28°C is the frontrunner at 49–56% and 29°C follows at 36%, indicating a significant cross-platform odds discrepancy [4]. The primary catalyst is the live temperature reading from Wunderground at the exact settlement time, as any deviation above 30°C would invalidate the current market consensus. Analysts note that the 2025 historical data for this airport shows similar summer volatility, reinforcing the need to watch for sudden heat spikes driven by continental airflows [5].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Kalshi vs Polymarket, which mirrors the Polymarket order book directly.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Kalshi vs Polymarket. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Kalshi vs Polymarket trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.