If you know us, you know we love the the outdoors and love to hike. Here's some great information we want to share with you about local trails.
A weather station at Foothills Nature Preserve decides whether three trails at Pearson-Arastradero Preserve stay open. When it records more than half an inch of rain in 24 hours, or an inch over seven days, the City of Palo Alto closes Bowl Loop, Woodrat and Wild Rye. It is the only preserve within a short drive of Portola Valley that publishes its closure trigger as a number.
On the other trails near town, a storm is judged differently depending on who manages the land and how you are getting around. This winter that matters more than usual. On October 20, San Mateo County said a strong to very strong El Niño is likely this fall and winter, and the Town of Portola Valley has been clearing storm drains and culverts and stocking sandbags. Across most of these rulebooks, hikers lose the least ground after a storm. Riders and cyclists lose the most.
The Preserve That Publishes Its Number
Palo Alto's preserve alerts page, updated September 18, 2026, sets out the rule for Pearson-Arastradero. A gauge reading closes the trails, but reopening also depends on how the ground looks:
Trails may be reopened after at least 48 hours of no rain and only when trail conditions are dry and tracks are not left by all user groups.
Forty-eight dry hours is only the minimum. The trails stay shut until a hiker, a rider and a cyclist can all cross the tread without leaving a mark, so in a wet stretch of El Niño weather, two days of sun may still not be enough. Only those three seasonal trails are affected. The city says every other trail at Arastradero stays open year-round. Most of the seasonal ones sit on the western side of the preserve, and Wild Rye is down in the lower area.
Foothills Nature Preserve, just up the road, works on a different footing. Horses are prohibited there, and bicycles stay on paved roads, never trails. That leaves less for a storm to restrict. One closure there has nothing to do with rain. The western segment of Fern Loop is shut for bridge replacement, and the city expects it to stay closed through the 2026/27 winter. The eastern segment is still open and connects to Costanoan Trail.
Midpen Decides Trail by Trail
The Midpeninsula Regional Open Space District runs Windy Hill, the preserve many in Portola Valley can see from home. It publishes no rainfall threshold and no fixed season. Its trail conditions page says closures can change "from day to day without notice" based on current and predicted weather. It also says high water can make creek crossings hazardous in winter storms, and that hazardous conditions can close an entire preserve. For cyclists the guidance is advice, not a rule: avoid dirt trails while it is raining or right after larger storms, when water is standing or running.
What Midpen does publish is a short list for each preserve of trails that may close to certain users when wet. At Windy Hill, the list is about horses:
- Betsy Crowder Trail
- Hamms Gulch Trail
- Lost Trail
- Razorback Ridge Trail
All four were listed as open to equestrians as of this week. Further out, the lists cover both bikes and horses. At Monte Bello they name Skid Road, White Oak, and the stretch of the Stevens Creek Nature Trail between Skid Road and Canyon. At Long Ridge they name Chestnut, Long Ridge and Peters Creek trails. La Honda Creek lists Folger Ranch Loop and Grasshopper Loop for equestrians, and Grasshopper Loop stays open to hikers all year. At Purisima Creek Redwoods, the trail to watch is Whittemore Gulch, which may close to both bikes and horses.
Thornewood, off La Honda Road, has its own issue. Bikes are prohibited throughout the preserve. Its current advisory says crossing Dennis Martin Creek on Bridle Trail is "not advised during high water events." At Russian Ridge, Midpen reported no trail closures at all.
In the Midpen system, almost every rain closure keeps hikers on the trail and turns horses or bikes back. The Arastradero rule closes the trail itself.
The Town and County Add Two More Versions
Portola Valley's own trail rules take a third approach. The Town says some wilderness trails close to horses during the rainy season to prevent trail damage, with the closures posted on the Town website. Bikes are allowed on paved paths and on certain unpaved trails near schools, but not on wilderness trails in any season. Those rules date to 2012. The Town's trail closures page shows the live status, and when last checked it listed no closures.
San Mateo County Parks keeps bicycles off unpaved trails at Huddart, Wunderlich and Edgewood all year, so a storm changes little for cyclists there. For riders, the county's Canyon Trail page at Huddart says the trail closes to equestrians in the rainy season and stays open to hikers and runners year-round. That same page warns that the trails section is being updated and some information may be out of date, and it points visitors to the current map or brochure.
Who manages it | What triggers a closure | Who usually loses access |
|---|---|---|
City of Palo Alto, Pearson-Arastradero | More than 0.5 inch in 24 hours or 1 inch in 7 days at the Foothills station | Everyone on Bowl Loop, Woodrat and Wild Rye |
Midpen, Windy Hill and the Skyline preserves | Current and predicted conditions, decided daily | Mostly equestrians and cyclists on listed trails; whole preserves in hazardous conditions |
Town of Portola Valley | Rainy season, posted on the Town site | Equestrians on some wilderness trails |
San Mateo County Parks | Rainy season on specific trails such as Huddart's Canyon Trail | Equestrians; bikes are already limited to paved areas |
Stanford, the Dish | No wet-weather closure in its posted notice | No one; open to hiking and jogging year-round |
Closures Already on the Calendar
Some closures this season have nothing to do with the forecast. These are already scheduled:
- Windy Hill, November 3 to 6. The connector between Hamms Gulch Trail and Eagle Trail closes for bridge repairs. Midpen suggests Alpine Road as the bypass.
- Coal Creek, through early April 2027. The Meadow Trail is closed for drainage and tread work. Midpen says the new trail has to settle over the rainy season before foot and bicycle traffic comes back. The page gives the reopening date as both April 5 and April 7.
- Foothills Nature Preserve, through the 2026/27 winter. Western Fern Loop stays closed for its bridge replacement.
- Wunderlich and Edgewood, wrapping up. The county scheduled culvert-repair closures on parts of Wunderlich's Alambique, Loop and Meadow trails from October 20 to 27, and on Edgewood Trail nearest the day-use area from October 22 to 27.
The Bridle Trail crossing at Thornewood and the Midpen equestrian lists can change between now and the next storm. Jasper Ridge works on a third clock. Public access there is only by appointment on docent-led tours, which go ahead in most weather and are canceled for heavy rain or severe-weather warnings.
The Paved Line Through Town, With One Gap
The county describes the Alpine Trail as a 7.6-mile paved path open to cycling and hiking. It runs along Alpine Road into Portola Valley, where the Town maintains it as the Dwight F. Crowder Memorial Bicycle Path. The Town counts more than 36 miles of paved paths and unpaved trails in its network, and its paved sections give a firm surface the day after a storm.
At the Menlo Park end, erosion has already broken the path. The City of Menlo Park reports that about 1,000 feet of the Alpine Trail between Sand Hill Road and Junipero Serra Boulevard is closed to pedestrians and bicycles. It points cyclists to the existing bike lanes on Santa Cruz Avenue as a detour. Check the city's project page before planning a loop toward Stanford.
So the morning after a storm, the questions to ask are who manages the trail and how you are traveling. On foot, the Dish, the Arastradero trails outside the seasonal three, Grasshopper Loop and Huddart's Canyon Trail all stay open under their posted rules. On a horse or a bike, check the Midpen lists, the Town's closures page and the Palo Alto gauge before you load the trailer or clip in.
Our own land questions tend to start where these trails do, with who manages the parcel next door, which easement crosses it, and what each one allows. If you are weighing a property near Windy Hill or along the Alpine Road corridor and want to understand what the land around it permits, Helen & Brad Miller are glad to talk it through. Reach Out Today.
