SAN DIEGO COUNTY, Calif. — As San Diego starts to head towards fall, we are still in the midst of one of the region's hottest summers, according to the National Weather Service.
"[We've had] record-breaking temperatures [and] 11 separate heat waves," said Meteorologist Alex Tardy from the NWS. "Most recently we had a heat wave go all the way to the coast."
That heat has continued to dry out the vegetation to all-time lows. The Anza-Borrego Desert had its hottest August.
"We had very little moisture, rain, and very little change in our temperatures," said Tardy.
The long-range models show very little change in the drier and warmer pattern.
"When we start looking into the fall [we see] what are we going to get more of or less of and the winter predictions are a continuation," Tardy said.
And as San Diego County heads into peak Santa Ana season there's a twist.
"We're also expecting La Niña," said Tardy.
La Niña is the cold phase in the Eastern Pacific along the equator where cold water sets up.
"Typically it's been associated with drier conditions in Southern California; not just in the fall but the entire winter is drier than usual," said Tardy.
However, over the past 10 years, there have been changes in weather patterns with dry El Niños and La Niñas.
"We see more of a narrow window, a shorter winter where we can get precipitation whenever we enter into La Niña," said Tardy.
That means a late start for rains that end early.
"All of this is a recipe for fire problems - and we already have fires now - but more fire weather problems as we go into fall and winter," Tardy said.
With La Niña, there is an amplified jet stream around the high and low pressure.
"You get on the wrong side of the jet stream, you get dry Santa Ana winds. You get on the right side and you see a lot of rain, [which is] sometimes beneficial [or] sometimes [causes] flooding," said Tardy.
Which is what happened in San Diego during its last rainy season with a surplus of rain.
"So it's important for people to understand where we've been, what we're in and where we're going," Tardy said. "And not just to hang your hat on La Niña or El Niño because they are just a small part of the equation."