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 market currently pricing any outcome above the baseline as impossible at 0% YES. This near-zero implied probability reflects a consensus that the day will remain cool, mirroring recent patterns where July highs in the capital frequently stall below 20°C due to persistent cloud cover and southerly winds. Historical data from comparable mid-July periods shows that when humidity sits near 88% and pressure falls, as seen in current forecasts, extreme heat events are statistically negligible, reinforcing the crowd’s dismissal of a hot day [2].

Traders should monitor the Met Office’s daily 9 AM update for any sudden shifts in the pressure gradient or wind direction, as a rapid transition to easterly flow could introduce dry air and spike temperatures unexpectedly. While no major weather announcements are scheduled for the immediate window, the dependency on Wunderground’s hourly logs means that a single anomalous reading could alter the settlement range, though such volatility remains unlikely given the falling pressure trend [2]. The value spot lies in the contrarian angle: if a high-pressure ridge builds overnight, the 0% price offers asymmetric upside, but the prevailing meteorological signals suggest the underdog (a hot day) remains firmly out of contention.

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 Who Will Win, 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 Who Will Win. 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.