Highest temperature in NYC on July 3?

Platform comparison

Market context

New York City’s LaGuardia Airport is currently experiencing a severe heatwave, with midnight temperatures hitting 94°F and daily highs surpassing 100°F, setting the stage for July 3, 2026, to potentially record extreme temperatures. Historical data shows LaGuardia reached 107°F on July 3, 1966, its highest ever for that date, while recent years like 2025 and 2021 also saw 100°F highs in late June and July[1][2][9]. The current crowd-implied probability of 0% for any specific high temperature range suggests traders are either dismissing the event or hedging against resolution uncertainty, yet the meteorological precedent indicates a non-trivial chance of temperatures exceeding 100°F.

Traders should monitor the National Weather Service’s heatwave updates and Wunderground’s real-time readings for LaGuardia, as these are the definitive settlement sources[5][6]. Recent forecasts predict daily highs between 81°F and 99°F for July 2026, but the ongoing heatwave has already pushed temperatures beyond these bounds, making the 100°F threshold a critical catalyst[6]. Platform comparisons reveal key divergences: Polymarket uses decimal odds and lower fees with minimal KYC, whereas Kalshi and Betfair require identity verification and offer implied probabilities with higher liquidity but stricter access, affecting how traders price this heat event across exchanges[3][7].

The settlement window closes on 2026-07-03 at 12:00 UTC, meaning any temperature recorded before then at LaGuardia will determine the outcome. With the heatwave persisting and records already broken, the 0% probability may reflect market inefficiency rather than meteorological reality, especially given the 1966 precedent of 107°F on this exact date[2][9]. Traders comparing platforms must weigh fee structures and KYC requirements, as these directly impact net returns when betting on extreme weather outcomes in prediction markets.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page compares Highest temperature in NYC on July 3? 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.

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.