Highest temperature in NYC on July 23?

Platform comparison

Market context

LaGuardia’s *highest temperature* on 23 July is the settlement input here, so the live market matters less than the airport’s actual afternoon peak. Polymarket currently prices 80–81°F at 72% and 82–83°F at 19%, which implies a fairly tight band around a warm but not extreme day. On Kalshi, the same kind of contract is usually easier to read in *implied probability* terms, while Betfair and Smarkets tend to present *decimal odds*; that changes how the market looks, but not the underlying weather risk. Fee treatment also differs: exchange-style books such as Betfair and Smarkets typically charge commissions on net winnings, whereas prediction-market pricing folds the cost into the bid/ask spread, which can make very short-dated weather contracts look less liquid than they are.

The historical framing is straightforward: late-July New York City highs often cluster in the upper 70s to mid-80s, so a 0% YES price for a specific band only means the crowd sees that band as effectively over, not that the day itself will be cool. Recent coverage has highlighted a broader hot spell in the city, with forecasts of 100°F readings during an earlier July heatwave, showing how quickly sentiment can swing when forecast highs move by a few degrees.[2] For this market, the key catalyst is the day’s actual temperature path at LaGuardia rather than central Manhattan forecasts, because sea breeze, cloud cover and storm timing can leave the airport a degree or two away from city-centre readings.

By settlement time, traders will be watching the National Weather Service forecast updates, thunderstorm timing and any shift in the marine layer, because afternoon convection can cap the maximum before late-day cooling sets in. The platform comparison matters here too: Polymarket’s crowd-implied probabilities can move rapidly on small forecast changes, while Kalshi’s regulated US access and traditional contract structure may attract different order flow; Betfair and Smarkets are often more accessible in decimal-odds form for UK users, but KYC and market availability can differ by jurisdiction.

Sources: 1 · 2

Methodology

This page compares Highest temperature in NYC 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 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

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.

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.

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.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Kalshi Alternative UK offers a fiat on-ramp via Klarna or SOFORT (DE/AT/CH) and converts internally to USDC for the Polymarket order book. T+1 processing.