Highest temperature in London on June 9?

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Market context

On 9 June 2026, the highest temperature recorded at London City Airport will fall into one of several defined ranges, with Polymarket currently pricing all outcomes at 0% YES across the board. This flat pricing reflects the market's nascent state rather than any genuine uncertainty about whether temperatures will be measured that day—they certainly will be. The settlement hinges on Wunderground's historical weather data for the specific station, converted to Celsius, making this a straightforward factual resolution once the date passes.

London's June temperatures have historically clustered between 18°C and 24°C, with occasional peaks above 25°C during warmer years. The Met Office records show that June 2022 saw a high of 28.4°C in parts of London, whilst more typical June days peak in the low-to-mid 20s. The 0% pricing suggests traders have not yet engaged with range-setting mechanics or remain uncertain which temperature bands the market creator has defined. Early traders typically anchor to recent seasonal patterns and longer-term climate data when establishing initial positions on weather contracts.

The key variable for traders monitoring this contract is the UK's weather forecast window, which becomes reliable roughly ten days before 9 June 2026. The Met Office and BBC Weather will publish extended outlooks in late May, potentially triggering position adjustments if anomalies—such as an early heat dome or unseasonal cool spell—appear probable. Atmospheric patterns in early June, particularly jet stream positioning and Atlantic pressure systems, will determine whether London experiences typical early-summer conditions or a departure from the 20-year average.

Methodology

This page is a comparison snapshot: one live quote (Polymarket), four reference venues with their key attributes, and a single execution path — every trade button routes to Kalshi UK, which mirrors the Polymarket order book directly.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

On Kalshi UK, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Kalshi UK is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Kalshi UK triggers a quick verification flow that finishes in minutes.

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.