Highest temperature in London on August 1?

Platform comparison

Market context

London’s highest temperature on 1 August is a **single-day, single-station** outcome, with settlement tied to the London City Airport Station reading on Wunderground rather than a broader city average. That matters because the market is not asking whether London feels warm in general, but whether the day’s peak lands in one specific Celsius band by 12:00 UTC on 1 August, which makes intraday timing and station-level microclimate the key variables.

The current crowd price of **0% YES** sits very far from the cross-platform picture. Polymarket’s own contract page showed **26°C** as the leading outcome at **64%**, with **25°C** at **21%** and **27°C** at **14%**, implying a central cluster around the mid-20s rather than an outright tail event.[2] That lines up with climatological context: London’s average August daytime highs are typically in the low-to-mid 20s Celsius, and even on the hottest day of the year the usual range is roughly 60°F to 74°F, or about 16°C to 23°C.[1][10] In other words, the market’s 0% print looks more like a stale or highly compressed market quote than a clean read on the weather itself.

For traders, the main catalyst is the short-range forecast into the event, especially whether the London forecast settles near 25°C–27°C or shifts lower after cloud, rain, or wind updates. The relevant dependency is the London City Airport Station high on the day, so a warm start does not guarantee the contract if the top reading lands before the settlement window or if later cloud cover caps the maximum. Recent market commentary on Polymarket described a consensus forecast around **26°C** under largely sunny conditions with light winds, which is consistent with the currently dominant band and suggests the main disagreement is about the exact temperature bucket, not the existence of summer warmth.[2]

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

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

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.