The combination of heavy rainfall saturating the soil and strong winds significantly increases the chances that branches and entire trees will come crashing down.

SAN DIEGO — This weekend’s storm could bring dangerous conditions for trees across the region, particularly eucalyptus trees that are prone to toppling.

“Saturated grounds and wind…. that is a bad combination,” said Ted Safford, a certified arborist who has worked in San Diego for the past half-century.

The combination of heavy rainfall saturating the soil and strong winds significantly increases the chances that branches and entire trees will come crashing down, according to Safford. Eucalyptus trees are particularly vulnerable because of their weight and density.

“Eucalyptus trees, because they are so heavy and so dense, are more likely to fail,” said Safford.

The danger posed by eucalyptus trees is not theoretical. In June, a 34-foot branch fell 60 feet from a eucalyptus tree at Villa La Jolla Park, fatally striking four-year-old Ronan Kerr on the head. In 2023, high winds brought down nearly three dozen eucalyptus trees in Balboa Park during a similar storm, and a eucalyptus tree fell on a parked car in Scripps Ranch due to rain-saturated soil.

Safford attributes eucalyptus trees’ vulnerability to their shallow root systems and the manner in which they are typically watered. 

“It’s all about how dense they are, how overgrown they are. They get heavy, and eucalyptus trees are outrageously heavy, and they’re prone to [breaking],” Safford told CBS 8. 

He added, “We give them water on the surface, so they tend to grow faster than their root system can grow to keep up with the heavy structure.”

Safford recommends that residents have their trees, especially eucalyptus trees, professionally maintained every two to three years. For those who have not done so, he has a clear message ahead of the atmospheric river expected this weekend.

“If they haven’t been conscientious about having them properly pruned, then they should be concerned, because they say this is an atmospheric river,” he said. “If you get through this one and you haven’t done it, do it!”