Highest temperature in NYC on July 4?

Platform comparison

Market context

The underlying event is the highest temperature recorded at LaGuardia Airport on 4 July 2026, which will determine the settlement of a prediction market with a current crowd-implied probability of 0% for the “YES” outcome. This near-zero valuation suggests traders view the specific temperature range in question as virtually impossible, yet historical data shows LaGuardia has recorded extreme heat, including a record midnight temperature of 94°F and a daily high of 104°F that surpassed Phoenix. Such outliers, documented by Fox Weather and the National Weather Service, frame how to interpret the current probability: while the range may seem improbable, New York’s summer heat has repeatedly defied expectations, with July 2026 forecasts indicating highs between 81°F and 99°F and overnight lows from 68°F to 83°F.

Traders should monitor real-time weather updates from Wunderground and AccuWeather, as these platforms provide the official resolution data and forecast dependencies. Recent reports from Fox Weather highlight that heatwaves can escalate rapidly, with LaGuardia’s 104°F reading breaking the prior record of 101°F, underscoring the volatility of July temperatures. When comparing platforms like Polymarket, Kalshi, Betfair, and Smarkets, note that Polymarket and Kalshi use implied probabilities while Betfair and Smarkets rely on decimal odds; fee structures also diverge, with Polymarket often charging lower fees but requiring KYC, whereas Kalshi mandates stricter identity verification. These differences affect liquidity and pricing efficiency on this specific market, where a 0% implied probability may reflect platform-specific risk aversion rather than pure meteorological certainty.

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Methodology

We read Highest temperature in NYC on July 4? 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

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.

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 supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Kalshi Alternative 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.