By the end of the 1990s, average temperatures in Los Angeles had risen 3 degrees fahrenheit above those of the 1940s. One key factor is believed to be the dramatic loss of orchards and farmland in Los Angeles County in favor of homes, buildings and roads. The increased percentage of concrete and asphalt served to absorb more solar heat and heat up surrounding atmosphere, causing a massive "urban heat island." Studies suggest that a massive planting of trees in the San Fernando Valley alone might lower average temperatures as much as 9 degrees. After the 1990s, average monthly temperatures overall dropped, although these contined to be warmer than those of the 1940s. Since 2010, however, overall average temperatures have again climbed. According to weather data analysis by Vox.com, in their 2019 article "Weather 2050", Los Angeles temperatures in 2050 are projected to average 3.5 to 3.6 degrees warmer than at present.
Temperatures in Degrees Fahrenheit
|Decade||Average Monthly Temperature||Temperature Increase Since 1880s|
Source: Western Regional Climate Center
-- High/Low & Average Temperatures by Month & Year for Downtown L.A.
-- Record Temperatures - Select Los Angeles County Locations