Highest temperature in London on June 17?

Platform comparison

Active sub-markets

Market context

On 17 June 2026, the highest temperature recorded at London City Airport will determine which range this market settles into. The settlement source is Wunderground's historical weather data for that specific station, measured in Celsius. The 0% crowd probability suggests either extreme confidence in a particular outcome or sparse liquidity; comparing across platforms reveals divergent approaches to weather markets. Kalshi, which operates under CFTC oversight in the US, typically offers tighter spreads on meteorological events but restricts non-US traders. Polymarket's Ethereum-based infrastructure allows global participation with lower barriers to entry, though fee structures and implied probabilities can drift during low-volume periods. Betfair and Smarkets, both UK-regulated, quote decimal odds rather than implied probability percentages, making direct comparison of this 0% figure less straightforward without conversion.

Historical June temperatures in London range from 11°C to 32°C, with the 30-year average high around 22°C. June 2022 saw a record-breaking heatwave that pushed temperatures above 30°C, whilst cooler Junes have remained in the mid-teens. The current probability distribution suggests traders are anchoring to recent seasonal norms rather than tail-risk scenarios. The Met Office publishes monthly climate summaries and seasonal forecasts; the long-range outlook for early summer 2026 will become clearer by April 2026, potentially shifting market prices as traders incorporate official guidance. Any significant atmospheric patterns—such as blocking highs or Atlantic storm systems—typically emerge in seasonal models 4–6 weeks before the event, offering traders a window to reassess their positions before settlement.

Methodology

This page compares Highest temperature in London on June 17? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. Live odds come from the Polymarket order book; the other venues' contract details are maintained manually because their APIs aren't directly comparable. Every CTA routes to Polymarket Alternative, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket Alternative, 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?

Polymarket Alternative 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.

What does it cost to trade on Polymarket Alternative?

Zero. Polymarket Alternative routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.

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.