Sun-loving Southlanders may be too quick to label any unseasonal gloom as "freak weather," but this spring, there's actual data to back the complaint.

Temperature data collected from multiple points around Southern California show the region has experienced a "reverse" meteorological spring, in which average monthly temperatures decrease instead of increase, and it's the first time that has happened in nearly a century, according to the National Weather Service.

A "meteorological spring" is defined as the months of March, April and May. Normally, May is hotter than April, April hotter than March, but in many locations around Southern California, we had a cooling trend the deeper we got into spring.

It's only the third time we've seen a reverse of the climatological norm since records began in 1877. Before this year, it happened in 1914 and 1921, NWS reports.

"It's just kind of a continuation of our strange weather we've had over the last couple of years, where we've been really warm throughout the winter months," Eric Boldt, NWS warning coordination meteorologist, told KPCC.

Average monthly temperatures for downtown Los Angeles in March, April and May were 68.2 degrees, 65.8 degrees and 64.2 degrees, respectively, according to NWS. The normal averages for the 30-year period from 1981 to 2010 were 60.6 degrees, 63.1 degrees and 65.8 degrees.

A similar trend was seen in many other locations in Southwestern California, the weather service said.

A full climate summary for May and for meteorological spring is expected Tuesday.