Highest temperature in London on June 30?

Platform comparison

Market context

The underlying event is the highest temperature recorded at London City Airport on 30 June 2026, a date that historically sits within the UK’s warm season but rarely breaches extreme heat thresholds. Current crowd-implied probability of 0% YES suggests the market expects the temperature to fall below the highest resolution range, likely under 30°C. This aligns with recent patterns: on 29 June 2026, Hampstead recorded a maximum of 24.6°C, while St James’ Park hit 33°C on a separate hot June day, indicating variability but not consistent extremes at EGLC [8][9].

For a power-user approaching this programmatically, the key is to monitor real-time Wunderground feeds and cross-reference with Met Office heat warnings, which trigger conditional order logic. Recent red extreme heat warnings were extended in London when temperatures reached 35.1°C, but such events are sporadic and often miss EGLC specifically [6]. Traders should watch for scheduled weather model updates from the Met Office and AccuWeather, which forecast 22–24°C for EGLC today, reinforcing the 0% probability [1][2]. No official announcements are pending, but dependencies include cloud cover and wind direction—southerly flows at 8 mph currently suppress peak heating [2].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on June 30? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

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?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Polymarket Review UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

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.