Highest temperature in London on July 19?

Platform comparison

Market context

London City Airport is set to record its peak temperature for 19 July 2026, with the outcome determining the settlement of a weather prediction contract. Current crowd-implied probability for the market resolving to any range above 21°C sits at 0%, while Polymarket data shows the 21°C outcome commanding a 100% frontrunner position, creating a stark divergence from the zero-probability implied by the specific contract title’s binary framing [1]. This alignment suggests traders view a mid-20s Celsius day as highly improbable, contrasting with typical July heatwaves in the capital where temperatures often breach 25°C.

Historical July peaks at London City Airport frequently exceed 25°C, yet the 2026 forecast currently indicates a cool start with temperatures hovering around 13°C and high humidity of 88% as of 2026-07-20 [2]. The 0% probability for higher ranges reflects a market consensus that a significant heat event is unlikely before the settlement window closes on 2026-07-19, a stance that diverges from long-term climatic averages where July 19 often sees warmer conditions. Traders should monitor the Met Office’s daily 12:00 UTC forecast updates and Wunderground’s real-time hourly history for the EGLC station, as any sudden shift in southerly wind flow or pressure drops could alter the temperature trajectory before the deadline.

Sources: 1 · 2

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 Best Prediction Markets UK, which mirrors the Polymarket order book directly.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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 Best Prediction Markets UK. 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.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

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.