Highest temperature in London on June 4?

Platform comparison

Active sub-markets

Market context

On 4 June 2026, the highest temperature recorded at London City Airport will determine which range this market settles into. The settlement window closes at 12:00 UTC that day, pulling data from Wunderground's historical records for the station. The 0% crowd probability suggests either extreme confidence in a specific range or sparse liquidity across the book—a common pattern on niche weather markets where traders cluster positions rather than distribute them evenly.

London's June temperatures typically peak between 20–24°C, with extremes rarely exceeding 28°C at the airport station, which sits in a built-up area with urban heat effects. Historical June records show the highest temperatures cluster in the 24–26°C band; days above 26°C occur roughly once per decade at this location. Comparing across platforms, Kalshi and Betfair handle weather markets differently: Kalshi's binary YES/NO structure forces traders into discrete outcomes, whilst Betfair's range-based approach mirrors this market's design more closely. Polymarket's decimal odds display can obscure implied probabilities for casual traders unfamiliar with the conversion, whereas Smarkets' fractional odds remain more transparent for quick mental maths.

Traders should monitor the Met Office's extended forecast from late May onwards, as high-pressure systems moving into the UK typically drive the highest June temperatures. The North Atlantic Oscillation phase and any early heat warnings issued by the UK Health Security Agency will signal whether conditions favour the upper or lower ranges. Wunderground's data feed updates daily, so confirmation of the exact settlement value becomes available immediately after 12:00 UTC on the day itself.

Methodology

This page compares Highest temperature in London on June 4? 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 Kalshi Alternative UK, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Polymarket settles via UMA Optimistic Oracle on Polygon. A proposer posts the outcome with a bond, the two-hour window runs, then the smart contract pays USDC.

Kalshi settles USD through the CFTC-regulated clearinghouse — the cleanest variant, with heavier KYC. Betfair Exchange settles in account currency (GBP/EUR), net of 2-5% commission. Smarkets follows the same model as Betfair with a lower default 2% commission.

FAQ

Where can I trade this market with the lowest fees?

On Kalshi Alternative UK, 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.

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, Kalshi Alternative UK triggers a quick verification flow that finishes in minutes.