Highest temperature in NYC on July 21?

Platform comparison

Market context

LaGuardia Airport will record a daily high temperature on 21 July 2026, measured in Fahrenheit and logged by the National Weather Service station there. This single data point—the peak reading across all hours of that calendar day—determines which temperature band the market resolves to. The settlement mechanism is straightforward: Wunderground's historical archive for KLGA station provides the official figure, accessible via their daily history tool with a simple unit toggle.

July temperatures at LaGuardia cluster tightly around seasonal norms. The 30-year average high for mid-July sits near 84°F, with typical daily highs ranging between 80–88°F. Extreme outliers do occur; the station has recorded 99°F in July during heat waves, though such events remain statistical tails. The 0% crowd probability suggests traders are either awaiting resolution data or treating this as a calibration exercise rather than an active forecast. Historical volatility in New York summer weather—driven by Atlantic moisture patterns and upper-level ridging—means any given July day can deviate substantially from the mean.

Traders monitoring this market should track National Weather Service forecasts issued in the days preceding 21 July, particularly heat advisories or excessive heat watches for the New York metropolitan area. The Climate Prediction Center's 6–10 day outlooks, updated weekly, signal whether ridge-building or tropical moisture intrusion is expected. For programmatic approaches, integrating Wunderground's API or conditional order logic tied to NWS forecast thresholds would allow automated position adjustments as the settlement date approaches and forecast confidence increases.

Methodology

This page reviews Highest temperature in NYC on July 21? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Kalshi Fees, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Settlement runs on-chain. Polymarket's contract logic separates YES and NO shares as conditional tokens; at resolution the winning share lifts to $1.00 and the losing one to $0. The outcome input comes from the UMA Optimistic Oracle, which secures against bad resolution with a bond + dispute window.

Once finalised, the smart contract pays USDC to the holders' wallets within minutes — no withdrawal fees beyond Polygon network gas. Kalshi settles in USD via CFTC clearance, Betfair in account currency net of commission, Manifold in play-money mana with no cash-out.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Kalshi Fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.