Highest temperature in Paris on July 23?

Platform comparison

Market context

Paris’s **highest temperature on 23 July** will be measured at the Paris-Le Bourget Airport Station and resolved from Wunderground’s daily history page, so the market is about the day’s *maximum observed reading*, not the daily mean or a city-wide estimate. With settlement ending at 12:00 UTC, the relevant question is whether the station’s afternoon peak lands in the 25°C band or pushes into a higher bracket before the cutoff.

The current 0% YES price looks far below the climatological baseline. Forecast pages for Paris in July point to typical highs of about **26°C** and lows near **16°C**, which implies that a 25°C outcome is ordinary rather than exceptional in late July[2][3]. That also helps explain why exchange-style books can diverge: Polymarket displays the outcome as an implied probability, while Kalshi and Betfair typically present prices as contract values or decimal odds, so the same weather view can look different once fees, spreads, and conversion from odds to probability are taken into account. Smarkets’ commission model can further change the all-in price, especially in thin weather markets.

For traders, the main catalysts are the actual Paris forecast evolution, any short-term heat or cloud cover changes, and whether the daily high arrives early enough to be captured before the 12:00 UTC settlement window closes. Local summer weather in Paris is often sensitive to frontal timing and afternoon convection, so late model updates matter more than broad seasonal averages. There is no special scheduled announcement driving this market; the practical dependency is the station reading itself, which can differ from nearby city forecasts because the market resolves on a single airport site rather than Paris as a whole.

Sources: 1 · 2 · 3

Methodology

This page compares Highest temperature in Paris on July 23? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. The live probability is the Polymarket mid; the comparison columns summarise each venue's fee structure, KYC, settlement currency and payment rails. Every CTA routes to Kalshi Alternative, 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

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.

Which platform has the deepest liquidity?

Polymarket — by a wide margin. Top markets reach $50-500M volume, Kalshi ~$200M cumulative, Betfair similar. Deeper liquidity means your trade moves the quote less.

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.

Are all these platforms regulated?

No. Kalshi is CFTC-regulated (US). Betfair and Smarkets are UK Gambling Commission licensed. Polymarket operates without explicit regulation — a different risk profile than a regulated sportsbook.