Highest temperature in Los Angeles on July 20?

Platform comparison

Market context

The market tracks the peak Fahrenheit reading at Los Angeles International Airport on 20 July 2026, a date that has already passed in the real world. With the settlement window closing at 12:00 UTC on that day, the 0% probability assigned to the “YES” outcome implies the crowd believes the event cannot occur or that the specific condition for resolution is impossible. However, Polymarket data shows the frontrunner outcome is 80–81°F at 100%, suggesting the market has effectively resolved to a specific temperature range rather than a binary yes/no event, creating a discrepancy between the binary listing and the underlying distribution [1].

Historically, mid-July in Los Angeles rarely exceeds 85°F at KLAX, with the 80–81°F range representing a typical summer high rather than an extreme heatwave. The current 0% implied probability for a binary “YES” likely stems from a misalignment in market framing, where traders are pricing the temperature range instead of a binary condition. Comparable cases from recent summers show KLAX highs clustering between 75°F and 83°F, with record-breaking heatwaves pushing temperatures above 95°F only during rare, sustained events [2].

For a programmatic trader, the key dependency is the Wunderground resolution source, which logs the highest temperature recorded at any time on 20 July. Automated bots should monitor the KLAX history page directly, as manual verification is unnecessary once the data is published. Recent weather reports confirm that summer heatwaves in Los Angeles are increasingly common, with authorities issuing energy-saving advisories and opening cooling centres during peak afternoon hours, indicating that temperatures in the 80s are statistically probable [2]. The market’s binary structure appears to be a misfit for the actual temperature-range resolution mechanism.

Sources: 1 · 2

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 Kalshi Fees. 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.

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.

Do I need to KYC for this market?

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