Highest temperature in London on July 19?

Platform comparison

Market context

The market tracks the peak temperature recorded at London City Airport on 19 July 2026, with settlement tied to Wunderground’s daily history for station EGLC. Current crowd-implied probability sits at 0% for any outcome, reflecting a lack of active pricing rather than a definitive forecast of cold conditions. This zero-liquidity signal often precedes a sharp repricing once early data points or model runs enter the market, particularly for weather events where historical baselines are well-established.

Historically, mid-July in London frequently sees highs between 22°C and 28°C, with the UK’s all-time record of 40.2°C set at Heathrow in 2022 during an extreme heatwave [3]. London City Airport, situated closer to the Thames and more urbanised than Heathrow, typically records slightly lower peaks but remains vulnerable to southerly heat advection. The current 0% probability is anomalous given these baselines; programmatically, traders would backtest EGLC’s July 19 history over the past decade to identify the most likely range, then deploy conditional orders once the market opens above a liquidity threshold.

Key catalysts include the Met Office’s 10-day forecast updates and real-time model outputs from ECMWF and GFS, which traders monitor for southerly flow anomalies. A recent BBC Weather snapshot for London City Airport shows current conditions at 13°C with southerly winds, though this reflects today’s 20 July data rather than the 19 July event window [1]. Traders should watch for any sudden shifts in the 500mb pressure maps or jet stream positioning, as these dictate whether a heat dome develops over the UK in the coming days. No official announcements are scheduled, but the Met Office’s daily 09:00 GMT forecast release remains the primary dependency for price discovery.

Sources: 1 · 2 · 3

Methodology

This page is a comparison snapshot: one live quote, four reference venues with their key attributes, and a single execution path — every trade button routes to Kalshi Fees, which mirrors the Polymarket order book directly.

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'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 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.