Highest temperature in London on July 21?

Platform comparison

Market context

On 21 July 2026, the highest temperature recorded at London City Airport Station will settle into one of several defined ranges. The resolution will draw from Wunderground's historical weather database, capturing the peak reading across all times on that calendar day in degrees Celsius. This market operates within a settlement window closing at 12:00 UTC on the resolution date, after which no further trades execute.

London's July temperatures have historically clustered between 20–25°C, with occasional peaks above 28°C during heat waves. The 0% crowd probability suggests traders are pricing in either extreme confidence in a specific range or sparse liquidity across the full spectrum of outcomes. Comparable July markets in prior years show that London rarely exceeds 30°C; the record for July stands at 34.3°C (set in 2022), making upper-range outcomes statistically unlikely but physically possible. Recent summers have exhibited greater volatility, with 2023 and 2024 producing several days above 25°C in mid-July.

Traders should monitor the UK Met Office's seasonal forecasts and Atlantic pressure patterns from late June onwards, as these drive July weather trajectories. El Niño or La Niña conditions influence European summer temperatures; current climate indices will clarify by spring 2026. Additionally, the market's accessibility depends on regulatory jurisdiction: traders in Germany face GlüStV licensing requirements; US-based participants may encounter CFTC reach depending on the platform's registration status. No-KYC access up to $1,500 typically applies to aggregate position size rather than single-market limits, meaning this weather contract may fall within simplified onboarding for qualifying jurisdictions, though verification thresholds vary by operator.

Methodology

This overview of Highest temperature in London on July 21? reviews the four comparable platforms from a regulatory perspective: which is accessible in your jurisdiction, where KYC kicks in, how the platform is classified by your country of residence. Live probability is the Polymarket mid; comparison columns show regulatory status, KYC thresholds and settlement options for each platform.

Resolution & payout

On Polymarket, resolution runs on-chain via UMA Optimistic Oracle. USDC payout is instant and automatic, with no KYC. Tax treatment depends on your jurisdiction — in the US, gains are usually ordinary income; in the UK, often capital gains. Consult a tax professional for your situation.

FAQ

How are winnings taxed?

Tax treatment varies by jurisdiction. In most countries, prediction market gains are treated as ordinary income or capital gains. We cannot provide tax advice — consult a tax professional for your specific situation.

Can I trade anonymously?

Pseudonymously, yes — up to the KYC threshold. Is Kalshi Legit stores an email address and wallet addresses rather than a legal name. Over $1,500 lifetime volume triggers KYC, after which identity is no longer anonymous.

What happens during a tax audit?

You're responsible for documenting your trades. Is Kalshi Legit exports a full transaction history (CSV/PDF) for tax reporting. In an audit you'll need to present these documents.

Are prediction markets gambling?

Legally unclear in most jurisdictions. Some interpretations classify them as wagering (gambling regulation applies), others as derivatives (financial regulation applies). There's no global precedent specifically for on-chain prediction markets.

Is there a withdrawal cap?

No platform-side cap. You can withdraw any amount provided KYC is complete. SEPA bank withdrawals over €15,000 trigger additional anti-money-laundering checks (statutory obligation for all platforms).