Highest temperature in London on July 19?

Platform comparison

Market context

London City Airport recorded a cool 13°C on the morning of 20 July 2026, following a week of unseasonably mild conditions across the capital rather than the scorching heat often associated with mid-July. The market currently assigns a 0% probability to any outcome above the lowest range, reflecting a consensus that the July 2026 heatwave, which began on 4 July, has already dissipated without leaving a residual high-temperature spike for the 19th [3]. Historical data from similar post-heatwave periods in the UK suggests that once the primary warm air mass breaks, temperatures typically stabilise or drop, making a sudden peak on the final day of the settlement window statistically improbable.

Traders should monitor the immediate forecast for the London City Airport Station as the primary catalyst, specifically watching for any unexpected southerly wind shifts that could reintroduce warmer air from continental Europe before the 12:00 UTC settlement deadline. While the current BBC Weather report indicates falling pressure and high humidity, a rapid change in these variables could alter the trajectory, though the crowd-implied probability of 0% suggests the market views such a reversal as negligible [2]. The resolution source, Wunderground, will capture the daily maximum, meaning even a brief afternoon spike could technically resolve the market, yet the prevailing meteorological trend points firmly toward the 21°C frontrunner outcome dominating the probability space [1].

Sources: 1 · 2 · 3

Methodology

Political prediction markets differ structurally from sports betting: thinner liquidity, longer settlement windows, higher sensitivity to single news events. This page shows the live Polymarket quote for Highest temperature in London on July 19? plus platform attributes for the three reference venues, so you can see at a glance where the deepest market for this question sits.

Resolution & payout

Political markets typically settle on official candidate or agency confirmation. Polymarket uses UMA Optimistic Oracle: a proposer posts the outcome with a bond, the two-hour window opens, then the smart contract pays USDC.

Kalshi settles USD via CFTC clearinghouse, with clearly defined resolution sources (e.g. AP race calls for elections). Betfair settles after the official outcome is registered with the league or agency. Manifold is play-money.

FAQ

What resolution source is used for elections?

Polymarket defines the source per contract — usually Associated Press (AP Race Call), Reuters or the official electoral commission. The source is stated in contract details before the market opens.

Can prediction markets influence election outcomes?

Markets reflect expectations rather than create them. Studies show public-facing markets can anchor expectations, but don't influence the underlying outcome. Political markets are information, not advocacy.

How fast do political markets react to news?

High-liquidity markets move within seconds to minutes. A Trump tweet on the economy can shift the "Trump 2024" market 2-5 points before mainstream media has written anything.

Are political prediction markets legal in my country?

It varies. They sit in legal gray areas in most jurisdictions. Polymarket is geo-blocked from US/UK/EU; some broker frontends have a different geo footprint. Trade only with capital you can afford to lose, and only if you understand the legal status in your jurisdiction.

Which political events have the biggest volume?

US Presidential election, party nominations (DNC/RNC), Senate majorities, individual state outcomes (Pennsylvania, Michigan, Wisconsin), and major European elections. Peak markets reach $50-500M per event.