Highest temperature in London on June 24?

Platform comparison

Active sub-markets

Market context

London City Airport is expected to face its warmest June day of 2026, with the crowd-implied 76% probability favouring a maximum temperature of 35°C or below. This outlook contrasts sharply with the 23 June reading, where the market assigned 100% certainty to a peak of 32°C or lower, and the 25 June forecast, which suggests a daytime maximum near 35°C amid an ongoing UK heatwave[2][3]. Historical context shows Kew Gardens recently hit 26.6°C, marking the hottest day so far, yet Heathrow has already recorded 37.8°C, indicating significant spatial variance in London’s thermal profile that traders must weigh against the airport’s specific station data[5][9].

Traders should monitor the Met Office’s daily heatwave updates and the scheduled release of high-resolution temperature maps for the London Boroughs, as persistent high-pressure systems are driving the current surge[2]. The resolution hinges on Wunderground’s recorded maximum for all times on 24 June, a dependency that creates divergence between platforms: Polymarket displays decimal odds (70% for 35°C or below), whereas Kalshi and Betfair emphasise implied probability and fee structures that vary by KYC reach, often altering the effective payout for identical weather outcomes[1]. Smarkets’ lower fee model may attract volume from those betting on the 36°C outlier (24% probability), while Polymarket’s frictionless entry appeals to retail traders less concerned with cumulative costs[1].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest temperature in London on June 24? 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.

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 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.

Do I need to KYC for this market?

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