In a release issued Friday, the San Mateo County Parks Department stated that all county parks are to be closed indefinitely, in an effort to combat the spread of COVID-19.
After the “shelter in place” orders, put into effect earlier this month at the statewide level, the parks department saw “a surge in visitors last weekend.” According to the department, “park staff observed many visitors ignoring the Shelter In Place Order by driving to parks, congregating in groups and not maintaining six-feet of social distancing.”
Midpeninsula Regional Open Space District is taking similar preventative action, stating that parks “receiving high use may be closed without notice.” As of Saturday, the 28th, Windy Hill is the only of their 26 preserves to be closed, without any date set for its reopening to the public. Other popular Midpen parks, such as Skyline and Russian Ridge, have had their parking capacity restricted, though I had no issue parking at Skyline Ridge today.
California State Park trails are to remain open to hikers as of right now, but campgrounds and indoor facilities are closed indefinitely.
TL;DR be sure to look up whether your hiking location of choice is actually open, and wash your hands.