Highest temperature in London on June 19?

Platform comparison

Active sub-markets

Market context

The relevant event is the **highest temperature recorded at London City Airport Station on 19 June 2026**, with settlement tied to the Wunderground daily history page rather than to a live forecast or intraday average. London City Airport was already showing a hot early-summer set-up, with observed and forecast highs around **30°C** and clear or mostly clear conditions in the reporting available on 19 June, which is consistent with a top-end summer reading rather than a mild one.[3][4]

The present **0% YES** crowd price is hard to reconcile with the weather context and the contract design, because the market resolves to a specific Celsius range containing the day’s maximum, not to whether London as a whole felt warm. Comparable London City Airport weather markets have concentrated heavily around round-number outcomes when model guidance and station observations lined up near a clear threshold, and the live Polymarket page for this event was already pointing to **30°C** as the frontrunner.[1][2] That makes lower bands look hard to justify unless the station’s final recorded maximum ends up materially below nearby forecasts.

Traders should watch the station’s final Wunderground history entry, any late-day change in sea-breeze or cloud cover, and whether the airport observation site prints an update after the settlement window closes. In market terms, the main catalyst is not BTC or ETH flow but whether the last few hours of convection, wind shift, or delayed station reporting nudges the recorded peak across a bracket boundary, which is what determines the USDC payout.[1][5]

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically this overview focuses on on-chain pricing: Polymarket's live mid comes from the Polygon conditional-token order book and settles automatically in USDC. The other three venues — Kalshi, Betfair, Manifold — are listed with their platform attributes, because they operate off-chain and a 1:1 comparison of contract mechanics isn't possible.

Resolution & payout

Settlement is on-chain via UMA Optimistic Oracle. A proposer posts the outcome with a bond, a two-hour dispute window opens, then the smart contract lifts winning conditional tokens to 1 USDC and sends payments to holders' wallets automatically. No withdrawal fees beyond Polygon gas.

Off-chain venues (Kalshi, Betfair, Smarkets) settle in local fiat through bank-side clearing — faster than SWIFT, slower than on-chain. Manifold pays no real cash.

FAQ

Where can I trade this market with the lowest fees?

On BTC Prediction, which mirrors the Polymarket order book at 0% fees. 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 it cost to trade on BTC Prediction?

Zero. BTC Prediction routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

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.