Highest temperature in London on July 16?

Platform comparison

Market context

London City Airport is recording 13°C this afternoon, a figure that aligns with the market’s 0% implied probability for any outcome suggesting extreme heat on 16 July 2026. Historical data for mid-July in London typically sees highs between 18°C and 24°C, with temperatures exceeding 30°C being rare but documented during recent heatwaves. The current crowd consensus effectively rules out the upper temperature brackets, reflecting a view that atmospheric conditions will remain moderate rather than volatile.

Traders should monitor the Met Office’s daily forecast updates and any sudden shifts in southerly wind patterns, which can transport warmer air from continental Europe. The settlement relies exclusively on Wunderground’s recorded maximum for London City Airport, meaning localized microclimate effects could diverge from broader regional forecasts. Recent weather bulletins from the BBC confirm falling pressure and high humidity, conditions that usually suppress peak temperatures rather than elevate them [2].

On Polymarket, the leading outcome is locked at 74–75°F (approximately 23.3–23.9°C) with 100% probability, while Kalshi and other platforms show no active lines for this specific date, creating a notable liquidity gap [1]. This divergence suggests the Polymarket crowd has already priced in a stable, non-extreme day, leaving little room for surprise if the forecast holds. Analysts treating this as a weather contract rather than a speculative bet would view the 0% YES probability as a rational reflection of current meteorological trends.

Sources: 1 · 2

Methodology

We track Highest temperature in London on July 16? 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

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.

Do I need to KYC for this market?

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