Highest temperature in Los Angeles on August 18?

Platform comparison

Market context

On 18 August 2026, the highest temperature recorded at Los Angeles International Airport will fall into one of several defined ranges. The market resolves using the Daily Observations table from Weather Underground rather than the summary Day High & Low figure—a distinction that matters when intraday temperature spikes occur before official peak reporting times. For programmatic traders, this means building queries against Wunderground's granular observation API rather than relying on headline figures that often lag behind actual recorded maxima.

Los Angeles August temperatures cluster predictably between 75–85°F at the airport station, with historical August averages around 79°F. The 0% crowd probability suggests the market may be miscalibrated or that traders are waiting for range definitions to clarify which buckets carry meaningful odds. Comparable August 18ths over the past decade show variation: 2023 peaked at 81°F, 2022 at 84°F, and 2019 at 80°F. This historical spread indicates the outcome is genuinely uncertain rather than a near-certainty, making the current probability assignment suspect for conditional order strategies.

Traders should monitor the National Weather Service Los Angeles forecast updates through mid-August, particularly any marine layer persistence or heat dome formation across Southern California. Wunderground's station-level data feed updates hourly, allowing automated systems to track real-time observations against range thresholds. The settlement window closes at midday UTC on 18 August, creating a tight window for final position adjustments once morning observations confirm whether the day is tracking toward cooler or warmer extremes.

Methodology

This page reviews Highest temperature in Los Angeles on August 18? across five venues. The live probability is the Polymarket mid-price, sourced directly from the on-chain Polygon order book; the comparison columns benchmark each venue on fee structure, KYC, settlement currency and payment rails. Every CTA routes to Kalshi Fees, which mirrors the Polymarket order book at 0% fees.

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.

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 Kalshi Fees 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.