Highest temperature in NYC on July 21?

Platform comparison

Market context

LaGuardia Airport will record a peak temperature on 21 July 2026, with the market currently pricing all temperature ranges at zero probability—a mathematical impossibility that reflects either extreme illiquidity or a technical issue in crowd pricing. The settlement hinges on the highest reading captured across all hours that day at the station, converted to Fahrenheit and matched against predefined brackets.

New York's July temperatures cluster reliably between 82–88°F at LaGuardia, with historical extremes reaching into the low 90s during heat waves. The 30-year average high for mid-July sits around 84°F. Anomalous readings above 95°F occur roughly once per decade during the city's most severe summer events; readings below 75°F are exceptionally rare. The current zero-probability consensus suggests traders have either abandoned this market or the platform has failed to populate outcome brackets, leaving no meaningful signal about expected conditions.

The National Weather Service Northeast office issues seasonal outlooks in early July that typically frame whether the summer will trend warmer or cooler than normal. Any Atlantic hurricane activity or tropical moisture intrusion in late July could suppress temperatures, whilst a stalled high-pressure system would elevate them sharply. Historical precedent shows that early-July forecasts rarely predict specific daily peaks with useful accuracy more than two weeks ahead, making near-term catalyst monitoring—mid-July heat advisories, jet stream positioning, and upper-atmosphere pressure patterns—more relevant for traders entering positions closer to settlement.

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

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

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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.

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.

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.