Highest temperature in London on July 6?

Platform comparison

Market context

The highest temperature recorded at London City Airport on 6 July 2026 will determine the outcome of this contract, with the market currently pricing the 32°C band at 38% and the 33°C band at 29%[1]. Despite the crowd-implied 0% probability for a "Yes" on lower thresholds, the on-chain mechanics on Polygon using USDC and conditional tokens reflect a strong belief in a hot day, driven by thin volume that can reprice rapidly with new data[5].

Historical precedents frame this outlook, as London observed its highest ever temperature of 40.2°C at Heathrow and St James's Park on 19 July 2022, while the highest daily minimum recorded was 25.8°C in Kenley on the same date[2]. Recent local data shows 5 July 2026 reached a maximum of 29.4°C, suggesting the heatwave is active and could push 6 July into the 30°C+ range, making the current 0% probability for lower bands appear misaligned with the trend[10].

Traders must monitor the immediate weather forecast for wet and breezy conditions moving into southern England on 4–5 July, which may suppress temperatures temporarily before a potential rebound[4]. The primary catalyst is the upcoming National Weather Service update for London City Airport (EGLC), as any shift from the current mild 15–17°C forecast to clearer skies could trigger a sharp repricing of the 30°C and 32°C bands[6]. The settlement window closes at 12:00 UTC on 6 July 2026, requiring the first data point from Wunderground to resolve the market[1].

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

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

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 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.