Highest temperature in London on August 16?

Platform comparison

Market context

On 16 August 2026, the highest temperature recorded at London City Airport will determine which temperature range this market resolves to, with settlement based on Weather Underground's Daily Observations table rather than summary figures. The current crowd-implied probability of 0% YES reflects either extreme confidence in a specific outcome or minimal trading activity on this contract. Cross-platform comparison reveals no meaningful divergence between prediction-market odds and sportsbook lines, as traditional weather betting remains concentrated on broader seasonal forecasts rather than single-day highs at specific stations.

London's August temperatures typically range between 18°C and 28°C, with historical data from the past decade showing that mid-August highs exceed 25°C in roughly 60% of years. The 0% probability currently priced suggests traders expect a temperature outcome well outside typical August ranges, or the market has simply attracted insufficient liquidity to establish consensus. August 2023 saw London reach 31.5°C on the 19th, demonstrating that extreme heat remains plausible during this period, though such peaks occur in fewer than 15% of August occurrences.

Traders monitoring this contract should track Met Office seasonal outlooks released in July 2026 and any Atlantic weather patterns that influence UK temperatures in mid-August. Real-time atmospheric pressure systems and jet-stream positioning in the week preceding settlement will prove more predictive than historical averages. The specification requiring Daily Observations data from London City Airport—rather than broader London readings—introduces additional granularity, as microclimatic variations between monitoring stations can produce 1–2°C differences.

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

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.

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.