Highest temperature in London on July 4?

Platform comparison

Market context

On 4 July 2026, the London City Airport Station will record its highest temperature in degrees Celsius, a real-world event that determines the settlement of this prediction market contract. Today, Polymarket prices the YES outcome for any temperature range at 0%, reflecting the crowd’s near-total certainty that the day will not breach the threshold required for a payout. This pricing sits on the Polygon blockchain, where USDC funds conditional tokens tied to temperature ranges, and the market will resolve only when Wunderground publishes the official daily high for EGLC.

Historically, July is London’s hottest month, with average highs around 22°C (72°F), yet extreme heatwaves have pushed temperatures significantly higher. In July 2022, London recorded its first 40°C day, reaching 40.2°C at Heathrow and St James’s Park, while a 2025 heatwave in the third week of July also produced notable extremes across the British Isles [7][9]. These cases frame the current 0% probability as unusually cautious, given that even moderate summer days at EGLC often exceed 20°C, and the settlement window includes the full 24-hour period.

Traders should monitor the Met Office’s daily forecast updates and any sudden shifts in southerly wind patterns, which can drive heat into the city. The BBC Weather forecast for 4 July 2026 currently predicts a high of 15°C (61°F), but this may change if a heat dome develops [1]. Additionally, the National Weather Service’s real-time METAR data for EGLC will provide early indicators of temperature trends [3]. No official announcements are scheduled, but the dependency on Wunderground’s final data release means traders must watch for any delays or discrepancies in the settlement feed.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in London on July 4? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Polymarket Scam?, which mirrors the Polymarket order book at 0% fees.

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 Scam?. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Polymarket Scam? 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.