Highest temperature in NYC on July 21?

Platform comparison

Market context

New York City's highest temperature on 21 July 2026 will be measured at LaGuardia Airport and settled against historical weather records. The current 0% crowd probability suggests either extreme confidence in a specific temperature range or minimal trading activity on this particular outcome bucket. Across platforms, this type of weather contract reveals structural differences: Kalshi's binary or narrow-range format contrasts with Polymarket's broader categorical bins, whilst Betfair and Smarkets typically offer decimal odds that require manual conversion to implied probability—a friction point for traders accustomed to percentage displays.

July temperatures at LaGuardia historically cluster between 78–86°F, with the station's all-time July record of 103°F set in 1966. The past five years show mid-July highs averaging 82–84°F, providing a baseline against which outlier ranges should be evaluated. A trader assessing the current zero probability should cross-reference whether the market's resolution categories exclude the most likely outcome entirely, a common design flaw that collapses liquidity into a single bucket.

The National Weather Service issues extended forecasts roughly 10–14 days before settlement, with meaningful updates arriving in the final week of July. Climate patterns in mid-2026 remain unknown, but Atlantic hurricane activity and heat dome positioning typically influence Northeast temperatures by late summer. Traders should monitor NOAA's seasonal outlook releases and track whether any El Niño or La Niña conditions are forecast for that period, as these drive broader weather patterns affecting the northeastern United States.

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 Kalshi Alternative, 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.

Which platform is accessible globally?

Polymarket is geo-blocked in the US/UK/EU. Kalshi is US-only. Betfair and Smarkets are UK-restricted. Kalshi Alternative has a different geo footprint and routes to Polymarket's order book at 0% fees.

Which platform supports Klarna/SOFORT?

Directly: none. Polymarket accepts only USDC on Polygon. Kalshi Alternative offers a fiat on-ramp via Klarna or SOFORT (DE/AT/CH) and converts internally to USDC for the Polymarket order book. T+1 processing.