Official observations from the Los Angeles International Airport (KLAX) station, as reported by Weather Underground—the market's resolution source—confirm the highest temperature on April 15, 2026, peaked at 69°F around 3 PM local time, driving the 100% market-implied probability for the 68-69°F outcome. Persistent marine layer stratus clouds, about 1,000 feet deep per National Weather Service analyses, limited solar insolation and daytime heating, aligning with the day's normal maximum of 68°F and partly cloudy conditions with no precipitation. This reflects strong model consensus pre-event on cool advection and coastal stratus typical for mid-April in Southern California. Post-measurement challenges are minimal, though rare quality-control revisions to hourly ASOS data could theoretically nudge the peak by 1°F if instrument anomalies emerge.