San Diego's average temperature of 76.8 degrees from July 1 to Aug. 20 is the hottest on record for that 51-day period, the National Oceanic and Atmospheric Administration announced Wednesday.
The previous record was 76.6 degrees set in 1984.
"For whatever reason the early '80s had warm summers," NOAA meteorologist Alexander Tardy said, noting that ocean temperatures were above normal and conditions were generally muggy. NOAA has documented similar trends this summer that partially contributed to a July streak of 17 consecutive days with an average temperature at 80 degrees or higher.
The same 51-day average in 2017 was 73.1 degrees, the 13th highest average all-time and much closer to San Diego's 30-year average, measured from 1981-2010.
Average temperatures for the July-to-mid-August stretch were also high in regions adjacent to San Diego. Escondido's average was also its highest ever at 81.6 degrees, nearly three degrees higher than the previous record of 78.7 degrees set in 1992, according to NOAA.
August tends to be the hottest month each year in most regions but Tardy believes San Diego could see a slight reprieve in temperatures in the coming week. "It should be the relatively coolest part of the month, but it'll still be above normal," he said.
NOAA takes temperature readings for San Diego at San Diego International Airport because its data dates to 1875 and the airport's climate is usually cooler than areas of the city further inland. The airport's data from 1875 is the longest-standing available to San Diego climate and weather researchers.
