Highest temperature in London on July 24?

Platform comparison

Market context

London City Airport’s highest temperature today will be set by whatever the afternoon brings, and the market settles on the day’s maximum in Celsius rather than the close, average, or an hourly reading. The crowd is currently pricing **0% YES**, which is consistent with the fact that the contract only resolves if the airport station posts a maximum in the specified range before the settlement cut-off. The relevant source is Wunderground’s daily history page for London City Airport, so the practical question is not “will London be warm?” but “where does the single-day peak land?”

Recent July comparables suggest the upper tail is plausible but not guaranteed. London has already seen a late-June/early-July heat spell this month, with temperatures reaching **34°C** in London and **34.0°C** in Teddington during the first July heatwave conditions, while typical July highs are closer to the low 20s Celsius.[1][2][3] That matters for platform pricing because Polymarket-style markets usually show an implied probability directly, whereas Kalshi and Betfair more often present contract prices or decimal odds that must be converted back into a percentage; Smarkets also takes a commission, so a tight weather range can look cheaper or more expensive depending on fee drag and spread. KYC availability also differs materially by venue, which affects who can access the market at all.

For a trader, the main catalysts are the day’s intraday weather evolution at London City Airport and any late guidance from the Met Office or local forecast services on cloud cover, sea-breeze effects, or showers, since these can cap the maximum well below broader London readings. July weather in London is usually volatile, with average highs around **23°C** and frequent rain, so a 30°C-plus print is a meaningful outlier rather than the baseline.[3][5] The strongest read-through will come from lunchtime and early-afternoon forecasts, because the settlement source uses the day’s highest recorded temperature, not the forecast maximum.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We read Highest temperature in London on July 24? from four platform perspectives: Polymarket (on-chain CLOB), Kalshi (CFTC-regulated exchange), Betfair Exchange (sports book exchange), Smarkets (peer-to-peer betting exchange). Polymarket's live mid is the canonical probability; the side-by-side columns benchmark fees, KYC, settlement currency and deposit rails so you can choose the venue that fits your jurisdiction and trade size.

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). On-chain settlement clears in minutes — the fastest payout path of the four.

FAQ

Polymarket vs Kalshi — which is better?

Depends on your location. Kalshi is CFTC-regulated, US-only with full KYC. Polymarket is global, on-chain, no KYC up to $1,500. Polymarket has ~10x higher liquidity but higher regulatory risk.

What does Polymarket cost vs Kalshi?

Polymarket: 0% fees, only Polygon network costs (~$0.01/trade). Kalshi: up to 7% per trade plus spread. For high-frequency traders, Polymarket is dramatically cheaper.

Is Betfair a Polymarket alternative?

Only partially. Betfair Exchange is UK-focused with a sports-betting emphasis; they have politics markets but with thinner liquidity than Polymarket. Settlement in GBP/EUR, 2-5% commission on winnings.

What about Smarkets as an alternative?

Smarkets is a UK betting exchange with a lower default commission (2%) than Betfair. Liquidity on political markets is below Polymarket, comparable to Kalshi. Geo-blocked in many jurisdictions.

Which platform is accessible globally?

Polymarket is geo-blocked in the US/UK/EU. Kalshi is US-only. Betfair and Smarkets are UK-restricted. Kalshi Alternative has a different geo footprint and routes to Polymarket's order book at 0% fees.