Highest temperature in London on July 21?

Platform comparison

Market context

The market concerns the highest temperature recorded at London City Airport on 21 July 2026, with settlement based on Wunderground historical data. The 1% crowd probability suggests traders expect temperatures to remain below the threshold implied by the lowest resolution bracket, reflecting baseline expectations for London summer weather.

London's July temperatures have historically clustered in the 20–25°C range, with extremes rare but documented. The UK Met Office records show that temperatures exceeding 30°C in London occur roughly once per decade during summer months, whilst readings above 32°C are exceptional events tied to specific atmospheric conditions—heat domes or sustained high-pressure systems. The 2022 heatwave, which saw temperatures peak at 40.3°C across parts of England, remains an outlier driven by continental air masses and exceptional circumstances. For a single day in mid-July at a central London location, the historical baseline suggests most outcomes cluster between 18–26°C.

Traders should monitor long-range weather forecasts released in early July 2026, which typically gain reliability within two weeks of the target date. The UK Met Office's extended outlook and European weather models will signal whether anomalous heat patterns are developing. Atmospheric blocking patterns—stationary high-pressure systems—are the primary catalyst for extreme temperatures; such patterns require specific jet-stream configurations that forecasters can identify weeks in advance. The settlement window closes at midday on 21 July, meaning final observations will be locked shortly after the morning's peak heating phase concludes.

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 21? 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

For political markets the resolution source is decisive. Polymarket defines a concrete source per contract (e.g. AP, Reuters, official electoral commission) and uses the UMA Optimistic Oracle as the on-chain dispute mechanism. With a clearly defined outcome the USDC payout lands within minutes of the final confirmation.

FAQ

How accurate are political prediction markets?

Historically more accurate than polls. Polymarket's Brier score on US 2024 elections was ~0.11 — better than 538 (~0.14) and every mainstream poll. Markets aggregate information with real skin in the game.

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.

Which platform has the deepest political liquidity?

Polymarket — by far. US 2024 presidential volume was ~$3.5B vs Kalshi (~$200M) and Betfair (~$120M). Where Polymarket is geo-blocked, brokers like Election Predictions UK route into the same order book at 0% fees.

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.

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.