Highest temperature in London on July 3?

Platform comparison

Market context

On 3 July 2026, London City Airport is forecast to reach a high of 26°C, with sunny intervals and mild humidity, making a temperature above 30°C highly improbable today [1][8]. The market currently prices the “YES” outcome (temperature exceeding a specific high threshold) at 0%, reflecting the crowd’s confidence that conditions will remain well within the moderate range for early July.

Historically, London City Airport’s July highs typically range between 21°C and 29°C, with 2026’s forecast aligning closely with this pattern [5][10]. In 2023 and 2024, the station recorded maximums of 27°C and 28°C respectively on similar dates, never breaching 30°C in the first week of July [9]. This consistency supports the 0% probability, as no recent comparable case suggests an extreme heat spike is imminent.

Traders should monitor the Met Office’s hourly updates and any sudden shifts in southerly wind flow, which could elevate temperatures marginally [3][7]. While no major heatwave announcements are scheduled, the National Weather Service’s real-time METAR data for EGLC will be critical for confirming whether the day’s peak stays near the 26°C forecast [3]. As of now, the on-chain conditional tokens on Polygon, settled in USDC, show no movement toward the YES side, reinforcing the market’s static stance until the settlement window closes on 3 July 2026 at 12:00 UTC.

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

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

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

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.

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.