Last year was the world’s hottest year by far since modern temperature records began in 1850, federal scientists confirmed Friday.
But amid the severe heat waves that baked Africa, China, Greece and Texas, the devastating wildfires that burned 45 million acres in Canada and the record loss of sea ice in Antarctica — all driven largely by climate change — something unusual happened in California. It was cooler than normal.
The state’s average temperature in 2023 was 58.2 degrees Fahrenheit. That temperature, compiled by NOAA, the National Oceanic and Atmospheric Administration, from daily readings at hundreds of weather stations, was California’s lowest annual average temperature in 12 years, when it was 57.4 degrees in 2011.
The last time Californians saw regular average temperatures like last year’s was in the late 1980s and early 1990s. Most years in the past decade have averaged between 60 and 61 degrees.
“California was one of the few regions on Earth that did not experience record or record-shattering warmth in 2023,” said Daniel Swain, a climate scientist at UCLA. “It really was in rare territory.”
To be sure, California’s average annual temperature is nearly 3 degrees hotter now than it was in 1900.
The mild year in 2023 doesn’t mean that climate change isn’t real or has somehow stalled, experts said Friday. It is continuing the long-term trend of warming the planet, which worsens droughts, wildfires and sea-level rise. The 10 hottest years globally since 1850 all have occurred since 2014, according to NOAA and NASA. Last year’s global record of 59.12 degrees was exacerbated by El Niño conditions and far exceeded what scientists were predicting.
“We’re frankly astonished,” said Gavin Schmidt, director of the NASA Goddard Institute for Space Studies, on last year’s world wide heat trend.
Despite California’s good fortune, last year’s average statewide temperature was still 0.8 degrees Fahrenheit hotter than the state’s 20th century average of 57.4 degrees.
But that’s significantly lower than the global increase, which last year was 3.22 degrees hotter than the 20th century average on land, and 2.12 degrees hotter than the 20th century global land and sea surface average.
A few degrees on average over a year doesn’t sound like much, but just like a person with a fever, they can make a difference in wildfires, heat waves and other extreme weather events.
How did California get lucky last year?
The parade of large atmospheric storms last winter that soaked the state and ended its three-year drought brought cooler, wetter conditions than normal, including the largest Sierra Nevada snowpack in 40 years.
The first three months of 2023 were the coolest January-to-March period in California since 1962, according to NOAA data.
That chilly spring helped avert the disaster of “The Big Melt” that Gov. Gavin Newsom and many state emergency response officials had worried about. Last spring, the fear was that huge amounts of Sierra snow could all melt at once during an early heat wave, causing intense flooding, as California suffered in 1997.
It didn’t happen, in large part because the spring heat wave never came in 2023. Despite some modest flooding of farmland in the San Joaquin Valley near Corcoran and other towns, the snow melted in a steady, mostly controlled way.
There also were fewer long periods last year when high-pressure ridges off California’s coast caused temperatures to spike as the state saw during its severe drought years of 2012-16 and 2020-22.
“High pressure blocks storms,” said Jan Null, a meteorologist with Golden Gate Weather Services in Half Moon Bay. “It cuts off the sea breeze, which is California’s natural air conditioning. When the sea breezes are cut off, the inland can warm up a lot. It’s like not being able to open the windows when your house heats up.”
California’s fire season was very mild as well in 2023, a trend that was largely linked to the weather.
Overall, a total of 324,917 acres burned in California last year on state and federal lands, according to Cal Fire, the state’s main firefighting agency. That’s just 19% of the 5-year average of 1.72 million acres.
“We had historic amounts of rain,” said Capt. Robert Foxworthy, a Cal Fire spokesman. “There were large sections of the Sierra Nevada that had snow all summer. And we didn’t have nearly as many red flag warning days — the large numbers of those hot, dry windy days like we have in the past.”
A big part of California’s good fortune last year was random luck, experts say.
When large amounts of numbers are averaged, there are always outliers. A baseball player with the best batting average in the league sometimes has days where he goes without a hit. A stock market that finishes up 20% for the year includes plenty of down days.
Parts of Greenland, Northern Australia and Alaska also were cooler than normal — small sections of blue on a world map that was nearly all red in 2023.
California did revert closer to the worldwide trend in November and December when temperatures warmed. The Sierra snowpack, the source of one-third of California’s water supply, on Friday was just 42% of normal for Jan. 12.
Could the cooler temperatures that prevailed in 2023 repeat again this year?
“It isn’t something we should expect to continue,” said Chris Field, a Stanford University climate change researcher. “Earth’s temperature is always a mosaic, but with climate change, the nature of the mosaic is increasingly that many areas are much warmer than normal, and a few are only modestly warmer than normal.”
Swain agreed.
“There are already strong signals that the rest of winter and spring are likely to be much warmer than average across California and the broader Southwest,” he said.
And fire season?
“It is way too early to make a prediction,” Foxworthy said. “We’re always hoping for more rain and snow.”