The oldest Baby Boomers, born in 1946, turned 67 this year. The tail end of the cohort, born in 1964, is 49.
People 65 and over comprised 17.1 percent of the city's population in the U.S. Census of 2010 — up from 15.6 percent in 2000. In California as a whole, seniors make up just 11.4 percent of the population.
Age by itself is a poor yardstick for predicting what people will need or what the community will look like.
"There are some very young 80-year-olds and some very old 60-year-olds," notes John Sink, vice president for programs at the nonprofit senior agency Avenidas.
But even as many Boomers vow to stay young through exercise and nutrition, chronic illness and "major life events" such as loss of a spouse inevitably come with the years.
Sink, who watches the numbers as he helps plan programs for "older adults," says, "We're studying the needs of folks very carefully.
"It's hard to go by age. You have to go by needs and interests."
An informal 2006 "white paper" on the impact of aging Boomers on Palo Alto — authored by a task force of community leaders, including city officials — raised the specter of a community where "upwards of 40 percent of our total population will be 55 years of age or older" by 2030.
That surprising projection was based on a survey of more than 300 Palo Alto Baby Boomers, who said they aim to age in their homes and remain active in the community, according to the paper, titled "Impact of the Aging Baby Boom Population on Palo Alto's Social and Community Services." It was co-authored by Richard James, then director of community services for the City of Palo Alto and Lisa Hendrickson, president and CEO of Avenidas.
The survey found that 80 percent of Boomers, who possess a higher education level than any past generation, have no plans to leave Palo Alto when they retire.
That, and other surveys confirm that "older adults going forward are not going to fit the same model of older adults of the last generation," Sink said.
"They have a different self-image, different view of independence and self-sufficiency and of what they want. They're very interested in health, fitness and nutrition."
High on the priority list for this group are strategies for "aging in place" — staying in the home, but using an array of supports to do things like help turn a mattress, clean the gutters or care for a family member.
Sink segments current and future users of older-adult services into a range of categories: lifelong learners, health seekers, practical-help seekers, volunteers and the frail elderly.
The relative sizes of those categories could shift as Baby Boomers age.
In a recent snapshot of Palo Alto's current senior population, gleaned from a January 2013 survey of Avenidas users, Sink found that 40 percent come to the agency for "lifelong learning" opportunities; a third come for practical help; one in five come for fitness and not quite one in five come for the weekday hot lunch program, La Comida.
Twenty percent of respondents (81 out of 398) described themselves as "caregivers" to a spouse or another household member, a figure significantly up from 13 percent in the past.
"People don't self-identify as caregivers, but we're starting to see that dial go up," Sink said.
"A big chunk" of today's seniors have no monthly housing expense, with mortgages fully paid off, he said.
However, nearly half the Avenidas survey respondents said they're living on incomes of less than $50,000 a year.
Sink said he has yet to fully analyze the survey and also is awaiting age-specific data from the 2010 Census, particularly on income.
"We take our responsibility as being experts on older adults in Palo Alto very seriously because part of our charter is to consult with the city on the needs of older adults in the community," he said.
As Palo Alto's over-65 population expands, so does its cohort under the age of 18.
The segment of the city's population that's under 18 grew from 21.2 percent in the 2000 Census to 23.4 percent in 2010.
In the same period, enrollment in the Palo Alto school district has grown from 10,000 to 12,400 as of last fall, and school leaders are looking to build new elementary and middle-school classrooms.