Highest temperature in London on July 3?

Platform comparison

Market context

The real-world event hinges on the peak temperature recorded at London City Airport on 3 July 2026, a date that historically sits within the capital’s warmest month. Current crowd-implied probability of 0% for any specific high range suggests the market expects a temperature outside the anticipated bands, yet historical data frames this as an outlier view. July in London typically delivers average daytime highs of 23°C, though Met Office records confirm heatwaves frequently push temperatures above 30°C, with a record 40.2°C hit at Heathrow in July 2022[1]. Recent trends indicate 2026 is likely to experience at least one sustained scorcher exceeding 30°C, making a 0% probability for standard ranges statistically precarious given the volatility of summer weather[1].

A power-user approaching this programmatically would monitor real-time dependencies like the Met Office’s daily forecasts and Wunderground’s hourly updates, which serve as the official resolution source. Traders must watch for sudden shifts in southerly wind patterns and humidity levels, as these catalysts can rapidly elevate temperatures; current observations show 88% humidity and falling pressure at London City Airport, conditions that often precede heat spikes[2]. Recent news from the Met Office highlights that July is statistically the warmest month, with heatwaves capable of soaring to record levels, reinforcing the need to track live data feeds for conditional order execution[1]. The settlement window ending 2026-07-03T12:00:00Z demands precise timing for algorithmic entries, ensuring no lag in capturing the day’s maximum temperature before the cutoff.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track Highest temperature in London on July 3? 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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Kalshi Fees trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

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.