Highest temperature in London on June 17?

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Market context

On 17 June 2026, the highest temperature recorded at London City Airport will determine which range this market resolves to. The crowd currently assigns zero probability to any outcome, suggesting either illiquidity or uncertainty about which temperature band will occur. London's June temperatures typically range between 18–24°C, though heat waves can push readings into the high 20s or low 30s. Historical data from the Met Office shows that June extremes at London City Airport have reached 29.5°C (2015) and 28.9°C (2017), with more moderate years clustering around 22–25°C. The 0% probability across all ranges indicates the market lacks conviction rather than reflecting genuine impossibility—traders are likely waiting for seasonal forecasts to solidify before committing capital.

The UK Met Office will release its long-range forecast for June 2026 in the coming months, providing the primary catalyst for meaningful price movement. Spring weather patterns and sea surface temperatures in the Atlantic will influence whether June leans toward typical conditions or anomalous heat. Recent years have seen increased volatility in early-summer temperatures; the 2022 heatwave and 2023's cooler June demonstrate the range of outcomes possible. Traders should monitor atmospheric circulation patterns and the North Atlantic Oscillation index as June approaches, since these drive whether high-pressure systems establish over the UK. The settlement window closes at midday on 17 June, leaving no margin for late-day temperature spikes, making morning and early-afternoon readings decisive.

Methodology

This page reviews Highest temperature in London on June 17? across five venues. We show live odds for Polymarket-based markets (sourced from the Polygon order book); for other venues we list platform attributes, since the comparable contracts are not exposed via a public API on every venue. Every CTA points at Who Will Win — the application we operate, where you trade directly against the Polymarket order book at 0% fees.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Where can I trade this market with the lowest fees?

On Who Will Win, 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.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What does it cost to trade on Who Will Win?

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

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Who Will Win 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.