Highest temperature in London on July 5?

Platform comparison

Market context

The underlying event is the highest temperature recorded at London City Airport on 5 July 2026, a date currently forecast to bring rain, gusty winds and mild conditions hovering between 15°C and 19°C. With a wetter, blustery pattern moving into southern England, temperatures are unlikely to climb significantly, making a high-heat outcome improbable and aligning with the current 0% crowd-implied probability for a YES resolution.

Historical data frames this probability sharply: London’s highest ever temperature was 40.2°C on 19 July 2022, while the highest daily minimum reached 25.8°C in Kenley on the same day. In contrast, typical July highs in London average around 21°C, and recent alerts for 4–5 July 2026 confirm temperatures will not exceed 19°C, with wind and rain making conditions feel notably cooler[1][3]. This divergence between extreme summer records and current cool forecasts explains why sportsbook lines and analyst consensus treat a high-temperature event as virtually impossible.

Traders should monitor Met Office updates and real-time Wunderground data for any sudden shifts in cloud cover or wind speed, as these are the primary dependencies for temperature spikes. A recent weather alert confirms steady showers and gusts between 30–40 km/h through Friday morning, suppressing heat accumulation[3]. With settlement ending 12:00 UTC on 5 July, any unforecasted sun break late afternoon could marginally raise temperatures, but current schedules suggest no such catalyst exists.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

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.

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 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 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?

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