Highest temperature in NYC on July 21?

Platform comparison

Market context

On 21 July 2026, the highest temperature recorded at LaGuardia Airport will settle this market into one of several defined ranges. The National Weather Service operates the official observation station there, and Wunderground's historical database pulls directly from that feed, making the resolution source unambiguous. Unlike binary weather markets, range-based temperature contracts require traders to forecast not just direction but magnitude, introducing additional complexity around seasonal norms and anomaly risk.

New York's July climate typically peaks between 82–88°F at LaGuardia, though heat waves regularly push readings into the low 90s. The 0% crowd probability here likely reflects either a missing market listing on competing platforms or an unusually narrow range definition that excludes typical July highs. Kalshi and Betfair have historically offered temperature contracts with tighter spreads and lower fees (Kalshi's 2% settlement fee versus Polymarket's variable structure), which can shift implied probabilities meaningfully on identical underlying events. Traders comparing books should verify whether each platform's range buckets align; a 90–95°F bucket on one venue might map to 88–93°F on another, creating apparent divergence that's merely definitional.

The settlement window closes at midday UTC on 21 July, giving traders roughly 12 hours after typical morning lows but before afternoon peaks fully develop. Meteorological forecasts become reliable only 7–10 days prior; current long-range models carry substantial uncertainty. Traders should monitor the National Weather Service's extended outlook starting mid-July and cross-reference historical analogues from 2012 (record heat) and 2019 (moderate summer) to calibrate tail-risk positioning.

Methodology

This page compares Highest temperature in NYC on July 21? 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 Robinhood Prediction Markets, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Settlement is the biggest difference between the four platforms: Polymarket on-chain in USDC (instant), Kalshi USD via CFTC (T+1), Betfair and Smarkets in local currency via bank withdrawal (T+1 to T+3). On-chain settlement clears in minutes — the fastest payout path of the four.

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.

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.

Are all these platforms regulated?

No. Kalshi is CFTC-regulated (US). Betfair and Smarkets are UK Gambling Commission licensed. Polymarket operates without explicit regulation — a different risk profile than a regulated sportsbook.