Highest temperature in NYC on July 21?

Platform comparison

Market context

LaGuardia Airport’s hottest reading on 21 July is the real-world anchor here, and the market is sitting at 0% YES, so the crowd is effectively treating the target outcome as already dead. That makes the consensus very one-sided: the favourite is the lower-temperature outcome, while any upside case depends on an unusual late-July spike in city heat. In handicapper’s terms, the market looks priced for a normal summer day rather than an extreme one, so the only value angle is the contrarian tail risk if New York gets a sharp warm-up after a run of milder conditions.

Historically, the key frame is that LaGuardia can run hotter than much of the city on clear, humid afternoons, but its daily maximum still tends to cluster around the seasonal pattern rather than breaking far outside it. For this kind of settlement, traders usually focus on whether the day can clear the upper 80s or push into the 90s Fahrenheit, because those thresholds separate a routine July session from a genuine heat event. With the implied probability at zero, even a modestly warm forecast can look cheap to the underdog side if there is any credible chance of a broad, sunny, stagnant airmass over the airport.

The main catalysts are the short-range forecast, any heat advisories for the New York metro area, and the timing of cloud cover, sea-breeze effects and thunderstorms near the afternoon peak. The highest temperature is set by the daily maximum at LaGuardia, so the exact hourly track matters more than the day’s average. For traders, the consensus will usually move only if forecasters shift towards stronger ridge building, stronger humidity, or a delayed frontal passage that leaves the city trapped in the warm sector longer.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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

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.

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 Who Will Win 2026 trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.