Highest temperature in NYC on July 21?

Platform comparison

Market context

New York City's weather on 21 July 2026 will be measured against historical July patterns at LaGuardia Airport, where summer heat typically peaks in the low-to-mid 80s Fahrenheit. The current 0% crowd probability suggests traders are either uncertain about the settlement mechanism or waiting for seasonal forecasts to crystallise. July in New York historically produces temperatures ranging from 75°F to 88°F, with extreme heat above 90°F occurring roughly once every three to four years during the month.

The National Weather Service's extended outlooks, updated weekly through spring and early summer 2026, will be the primary catalyst for meaningful probability shifts. El Niño or La Niña conditions developing in the months preceding July could influence whether the Atlantic basin trends warmer or cooler than the 30-year normal. Historical precedent matters here: July 2019 saw LaGuardia reach 88°F as its daily high, whilst July 2022 peaked at 85°F. Traders should monitor climate pattern forecasts released by NOAA around April and June 2026, as these typically narrow the range of plausible outcomes for specific summer dates.

The settlement relies entirely on Wunderground's historical data for LaGuardia Airport Station, making the resolution straightforward once the day passes. The 12:00 UTC window closing time means all temperature readings through midnight local time will be captured. Given the market's current inactivity, early movement will likely come from seasonal weather enthusiasts rather than mainstream traders.

Methodology

We track Highest temperature in NYC on July 21? across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

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 Prediction Today. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

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.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Prediction Today trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.