Highest temperature in London on August 2?

Platform comparison

Market context

Polymarket is currently pricing this London heat contract as a low-conviction, near-balanced bet, with the leading outcome at **27°C** on **52%** and **26°C** on **26%**; the rest of the curve sits behind that, so the market is signalling a moderate summer warm spell rather than an extreme outlier. On Polymarket, traders are buying and selling **USDC**-backed shares on **Polygon**, and each correctly resolved conditional token pays **$1** when the London City Airport Station reading lands in the winning temperature band.

The main comparator is the recent pattern of London maxima clustering in the mid-to-high 20s Celsius during warm spells, rather than jumping into the 30s unless synoptic conditions are unusually strong. Met Office-linked market text points to strengthening high pressure, light winds and southerly flow as the setup behind the current 27°C lead, which is consistent with a summer day where the final print can still move a bracket either side of the front-runner. That makes the present 0% crowd-implied YES price for any single band look like a function of market spread rather than a hard view that no outcome can clear; in practice, the contract is settled by the highest observed value at the station, not by the noon snapshot.

For traders, the key catalysts are the morning-to-afternoon forecast updates, any late shifts in cloud cover, wind direction or shower risk, and the actual station observations that can push the day’s high into a different band before the first datapoint for the next date is published. Wunderground’s daily history page for London City Airport Station is the resolution source, so the relevant live input is the eventual maximum there, not broader London averages or city-centre forecasts.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page reviews Highest temperature in London on August 2? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to PolyGram, which mirrors the Polymarket order book at 0% fees.

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

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.