Highest temperature in London on July 19?

Platform comparison

Market context

The market tracks the peak Celsius temperature recorded at London City Airport on 19 July 2026, with settlement dependent on finalised Wunderground data for EGLC. Current crowd-implied probability sits at 0% for a "Yes" outcome, reflecting that the event date has already passed and no qualifying temperature range has been selected or confirmed by the crowd as the likely winner.

Historically, mid-July highs in London typically range between 22°C and 28°C, with extreme outliers like the 40.2°C recorded in July 2022 at Heathrow remaining rare anomalies for City Airport due to its urban microclimate and lower exposure to open heatwaves. The 0% probability suggests the crowd either expects a specific range to be excluded or has not yet converged on a resolution, which is unusual for a post-event market unless data latency or ambiguity persists.

Traders should monitor the official Wunderground daily history page for EGLC, where the final maximum temperature will be published once the 24-hour cycle closes and data is validated. Any delay in data finalisation could prolong settlement, as Polymarket requires all daily records to be locked before resolving. No external news catalysts apply here; the sole dependency is the automated update from the weather archive source, making this a pure data-verification play for algorithmic traders.

Sources: 1

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

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.

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.