The Warming of Los Angeles

Photo courtesy of Tpsdave &

By the end of the 1990s, average temperatures in Los Angeles had risen to almost 4 degrees Fahrenheit warmer than in the 1940s. This was believed to be due to the dramatic loss of Los Angeles County orchards and farmland in favor of buildings and roads. The increased concrete and asphalt served to absorb more solar heat and heat up the 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 Fahrenheit. After the 1990s, there was a drop in average monthly temperatures, although these continued to be higher than those in the 1940s and have again continued to climb.

Average Monthly Temperatures by Decade
Downtown Los Angeles, 1880s - 2010s

Decade Beginning: Average Monthly Temperature During Decade
1880 62.38o
1890 62.13o
1900 62.71o
1910 62.75o
1920 63.62o
1930 64.54o
1940 63.55o
1950 64.88o
1960 65.11o
1970 65.28o
1980 67.28o
1990 67.00o
2000 65.43o
2010* 66.13o

* Decade through March 2017

Source: Western Regional Climate Center