Visitors heading to Yosemite National Park are being warned about a terrifying park hazard involving “Summer Branch Drop” after a Google engineer was killed by a fallen tree limb.
Angela Lin, 29, was killed in a freak accident in the park when a branch from a giant sequoia tree fell and struck her on the head when she was hiking in the Tuolumne Grove with friends in July 2025.
The park said Monday that with the hot summer days it’s now “Summer Branch Drop” season, where a seemingly healthy tree suddenly loses a limb without warning.
A 29-year-old Google engineer was killed by a tree branch in a tragic accident in Yosemite National Park. cs.utexas.edu
A carved wooden sign announces the entrance to the Tuolumne Grove of giant sequoia redwood trees in Yosemite National Park in Yosemite Valley, California, in 2016. (Archive Photos) Getty Images
Officials said it happens most frequently in black oaks around Yosemite during the summer, on those particularly hot, calm afternoons, with no wind.
“Unlike most breaks due to wind, which occur where a branch attaches to the trunk, a break due to summer branch drop usually occurs three to 12 feet away from the trunk, along the length of the branch,” the message read.
“The branches that break are usually long and horizontal, as opposed to upright, frequently extending to or beyond the average tree canopy.”
“Summer Branch Drop” (SBD) season is a phenomenon where seemingly healthy trees suddenly lose limbs. Yosemite National Park
Hikers make their way to the Tuolumne Grove in Yosemite National Park in the central Sierra Nevada mountains of California on Thursday, Sept. 21, 2017. The grove is one of a Yosemite park ranger’s five favorite spots. (Tribune News Service) Tribune News Service via Getty Images
A thick layer of snow still covers the mountains above Highway 120 at Ellery Lake near Tioga Pass. Getty Images
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“While some limbs that drop show evidence of wounds or decay, many of these failed limbs appear to be quite sound,” the message added.
A shocking photo included with the post showed an oak tree with a massive split across a giant branch.
Officials said the cracks typically happen in older, less vigorous trees, noting once a tree loses a limb during this time, it is likely to happen again.
There are a few things visitors can do to prevent a possible tragedy or injury. Those include not leaving infants or elderly people directly under large oak trees.
Avoid pitching tents or setting up for a picnic underneath a black oak’s branches on hot summer days. Los Angeles Times via Getty Images
Hikers look at one of the Giant Sequoia trees in the Tuolumne Grove in Yosemite National Park. Tribune News Service via Getty Images
Ellery Lake, located along Tioga Pass near Yosemite National Park’s east entrance. Getty Images
Avoid pitching tents or setting up for a picnic underneath a black oak’s branches on hot summer days. “If you hear a loud crack from overhead, quickly run away from the tree itself,” officials said.
“Steering clear of already affected trees is also a great way to stay safe from this hazard and helps park operations act on and maintain tree health accordingly. “
They also are asking for the public’s help in notifying rangers if you see a tree or branch fall.
It is unclear how many people in the past have been injured or killed by this park hazard or if SBD was the reason the branch fell from the massive tree and struck and killed Lin.
The Post reached out to the park for more information.
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