Highest temperature in London on July 21?

Platform comparison

Market context

London City Airport is currently recording 13°C with heavy humidity and falling pressure, a stark contrast to the extreme heat required to trigger the 1% YES outcome on this weather contract. The market resolves to the specific Celsius range containing the day’s peak temperature at the EGLC station, with settlement finalising at noon UTC today.

Historical data for mid-July in London shows that temperatures exceeding the thresholds implied by the YES side are rare anomalies, typically occurring only during intense continental heatwaves like those in 2018 or 2022. Current meteorological conditions, including the 88% humidity and southerly 8mph winds, align with the crowd’s 99% confidence that the day will remain cool, mirroring the typical summer profile rather than the record-breaking spikes needed to shift the probability.

Traders should monitor real-time updates from BBC Weather and Wunderground’s hourly history for the EGLC station, as the settlement window closes within hours. No political catalysts, campaign disclosures, or scheduled debates influence this weather-dependent resolution, making the sole driver the immediate atmospheric data. The market leans entirely on the absence of a sudden temperature spike, with the current 13°C reading effectively locking in the outcome before the 12:00 UTC deadline.

Sources: 1 · 2

Methodology

This page tracks Highest temperature in London on July 21? across four political prediction venues. Live odds come from the Polymarket order book (the deepest political prediction-market book). Kalshi is the CFTC-regulated US alternative, Betfair the established UK sports-exchange with politics markets, Manifold the open play-money variant. For users geo-blocked from Polymarket directly, brokers like Trump Prediction provide a 0%-fee route into the same order book.

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.

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.

Why do Polymarket and Kalshi differ on elections?

Kalshi must follow CFTC compliance — strict definitions, clear resolution sources, US citizens only with KYC. Polymarket operates globally without CFTC oversight — deeper liquidity, but also higher regulatory risk.

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.