Highest temperature in London on June 19?

Platform comparison

Active sub-markets

Market context

London City Airport is already trading off a warm start to the day, with BBC Weather showing a **sunny** Friday and a forecast high of **86°F** for London City Airport, while the current observation is **13°C** with light rain at the station used for settlement[1]. For this market, the key number is the *daily maximum at London City Airport Station*, not the citywide headline, so short-lived midday heating or a late-afternoon cloud band can still shift the outcome even if the morning looks benign[1][7].

The 0% Yes crowd price implies the market is effectively treating a high June outcome as impossible, which is hard to reconcile with the seasonal baseline. WeatherSpark classifies mid-June as part of London City Airport’s warm season, and June commonly sits in the city’s more temperate summer regime rather than winter-like temperatures[5]. On competing books, the same event may be displayed as decimal odds on Betfair and Smarkets rather than implied probability, so a price that looks tiny in per cent terms can still be quoted as a long decimal on those exchanges; Polymarket and similar venues usually show the probability directly, and any comparison also has to account for access frictions such as KYC scope and market fees, which can differ materially across platforms.

The main catalysts are the Met Office and airport-specific forecast updates, plus any last-minute change in cloud cover, wind or shower timing before the settlement window closes at noon UTC, because the resolution source is the full-day high from Wunderground’s London City Airport Station page[7][1]. The current official-style airport feeds already show a mild, unsettled pattern with light rain and modest winds, but the BBC and Met Office forecast pages can update rapidly through the day, and the realised maximum may occur well before the market’s noon cutoff if conditions briefly clear earlier than expected[1][7].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest temperature in London on June 19? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. Live odds come from the Polymarket order book; the other venues' contract details are maintained manually because their APIs aren't directly comparable. Every CTA routes to Polymarket Alternative, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Settlement is the biggest difference between the four platforms: Polymarket on-chain in USDC (instant), Kalshi USD via CFTC (T+1), Betfair and Smarkets in local currency via bank withdrawal (T+1 to T+3). Polymarket Alternative routes every trade directly into Polymarket's on-chain settlement, which is why payouts land fastest.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket Alternative, 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.

What does it cost to trade on Polymarket Alternative?

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

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.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, Polymarket Alternative triggers a quick verification flow that finishes in minutes.

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.