The Bay Area faces a string of cold systems this week that could bring snow to higher ridgelines and hail down to sea level. Forecast models through Wednesday morning point to measurable accumulation on peaks such as Mount Hamilton, where the National Weather Service expects 4 to 8 inches between 6 a.m. Tuesday and 4 p.m. Wednesday. Lower elevations are less certain: a freezing level near 2,500 feet would allow wet snow or brief accumulation on some ridgelines, while thunderstorms could deposit hail even in urban neighborhoods. Residents should expect periods of heavy rain, strong gusts and localized lightning during Tuesday’s cold showers.
Key takeaways
- Mount Hamilton (4,200 ft) is under a winter weather advisory for 4–8 inches of snow from 6 a.m. Tuesday to 4 p.m. Wednesday (NWS Monterey).
- Forecasters predict temperatures at 5,000 feet around 25–27°F Wednesday morning, implying a freezing level near 2,500 feet.
- Peaks in the Diablo range and similar ridgelines could see up to a half-foot (≈6 inches) of snow in stronger showers Tuesday–Wednesday.
- Heavy showers could produce hail that temporarily whitens surfaces as low as sea level, including San Francisco and Oakland, especially during convective bursts.
- A later storm Thursday may push the snow line lower in parts of the North Bay, possibly approaching 1,000 feet in some forecasts.
- Big Sur hills could receive up to 1.5 feet of snow; Lake and Mendocino counties have warnings for 4–8 inches above 2,500 feet with locally higher amounts.
- The Sierra Nevada will receive substantial snowfall and remains the primary area for multi-foot accumulations through Thursday.
Background
California’s coastal state often sees winter storms that originate over the Gulf of Alaska; this week’s pattern is a relatively straight trajectory of cold air and Pacific moisture into Northern California. The Bay Area is accustomed to rain and wind during winter storms, but snow at the elevations under discussion becomes noteworthy because it can occur near commonly traveled ridgelines and overlook points. February 2023 produced rare low-elevation snowflakes across Bay Area hills when the freezing level dropped unusually low; forecasters are comparing this week’s cold pool against that benchmark. Sea-surface temperatures off San Francisco are warmer now—around 57°F—than during the 2023 event, and that ocean warmth will moderate coastal cold and reduce the risk of widespread lowland accumulation.
Mountain weather forecasting relies on observations and model soundings evaluated about 5,000 feet above ground to assess the depth of subfreezing air. A predicted 25–27°F layer at that altitude typically corresponds to a freezing level several thousand feet lower, but precipitation intensity, downward mixing from storms and coastal moderation can all change the outcome at specific sites. Local terrain plays a large role: windward slopes can see more accumulation while leeward valleys remain rain-dominated. State and county agencies monitor such advisories because snow, hail and wind together raise hazards for drivers, power infrastructure and trail users.
Main event
The first of the week’s systems arrived as rain and wind on Monday, then models show a lull late Monday before a stronger, colder pulse moves in. That colder air is forecast to arrive Tuesday into Wednesday, with scattered heavy showers that could include small hail and convective activity producing erratic gusts and lightning. The National Weather Service has issued a winter weather advisory specifically for elevations above 3,000 feet in the Santa Clara hills—including Mount Hamilton—calling for 4–8 inches of snow during the advisory window.
Showers on Tuesday evening look to be the most intense across the Bay Area, with a mix of cold rain, hail and snow at higher elevations. Forecasters note that heavy, wet snow or a rain–snow mix is possible along Skyline Boulevard in San Mateo County and atop Mount Tamalpais if showers are sufficiently deep and cold. Because snow can fall as much as 500–1,000 feet below the modeled freezing level, ridgelines near or above 2,000–2,500 feet will be most vulnerable to brief accumulation.
Mount Hamilton is the likeliest site for measurable sticking snow within local hills, in part because the 4,200-foot summit regularly records winter accumulation and has seen measurable snow every winter since 1989. The Lick Observatory on Hamilton’s summit remains closed for repairs after a December storm damaged equipment, but the peak itself will likely display visible snowpack. Farther north and inland, Lake and Mendocino counties have already seen upgrades to winter storm warnings for 4–8 inches above 2,500 feet, with locally higher amounts above 3,000 feet and potential impacts along sections of Highway 101.
Analysis & implications
For transportation, the primary concern is brief, localized impacts rather than regionwide closures. Roads at and above the advisory elevations—mountain passes and scenic byways—may require chains or traction advisories if precipitation falls as snow. At lower elevations, hail and heavy rain can create slick surfaces, reduce visibility and increase the risk of spinouts during convective bursts. Emergency managers and public works agencies typically stage crews when forecasts include quick-hitting, high-intensity showers in the hills.
Power infrastructure faces two separate stressors: wet, heavy snow can bring down branches and lines at higher elevations, while strong gusts and lightning can damage equipment at all elevations. Utility outage risk increases where wet snow loads coincide with mature trees along rural roads. Utilities and county offices often pre-position crews during multi-day cold storms, which helps reduce restoration times but does not eliminate short outages.
Public health and recreation implications are mixed. Cold, stormy conditions reduce outdoor event viability and can raise hypothermia risk for unsheltered populations; conversely, brief urban hail or a dusting on local overlooks will attract sightseers and photographers, creating temporary traffic congestion on access roads. For water resources, these storms add to seasonal snowpack at mid- and high elevations; however, the modest elevations and expected wet, heavy character of much of this snowfall mean runoff timing and reservoir benefit will differ from a high-elevation, light-snow event.
Comparison & data
| Location | Elevation | Forecasted snow |
|---|---|---|
| Mount Hamilton | 4,200 ft | 4–8 in (advisory) |
| Diablo range ridgelines | ≈2,500–3,800 ft | Up to ~6 in in heavier showers |
| Big Sur hills | Variable | Up to 1.5 ft possible |
| Lake & Mendocino (selected sites) | >2,500–3,000 ft | 4–8 in ; locally up to 14 in above 3,000 ft |
The table summarizes official advisory amounts and model-derived ranges. The Diablo range and Mount Hamilton stand out as the most likely local sites for measurable accumulation this week; coastal summits such as Mount Tamalpais are marginal because warm ocean air near the surface can melt snow unless showers are intense and cold. Sierra forecasts remain the most robust for multi-foot totals and are being tracked separately under winter storm warnings there.
Reactions & quotes
“You’re going to see the hills covered in snow in the East Bay,”
Matt Mehle, National Weather Service office in Monterey (paraphrased)
Mehle’s remark underscores localized visibility of snow across East Bay ridgelines rather than a low-elevation citywide event. His office issued the winter weather advisory that pinpoints timing and the 4–8 inch guidance for specific Santa Clara hills, guiding local preparedness.
“Expect intermittent heavy showers with hail and the possibility of brief accumulations on exposed summits,”
National Weather Service advisory (paraphrased)
The advisory language is targeted to travelers and local authorities, emphasizing both the expected accumulation on higher terrain and the potential for convective hail to affect lower elevations.
“Model soundings show a cold pocket aloft this week, but coastal moderation will limit lowland sticking snow,”
Regional meteorologist (paraphrased analysis)
That technical framing explains why similar atmospheric profiles can produce visible snow on ridgelines while leaving nearby cities wet and wind-swept.
Unconfirmed
- Whether snow will accumulate on urban streets in San Francisco or Oakland remains unlikely and model-dependent; any whitening there would most likely be from hail or brief sleet, not sustained snowfall.
- The forecast lowering of the snow line to ~1,000 feet on Thursday in parts of the North Bay is model-dependent and subject to revision as upper-air data are updated.
- Exact snowfall totals at specific ridgecrest parking areas (e.g., Skyline overlooks) are uncertain until convective showers actually pass over those spots.
Bottom line
This week’s pattern brings a genuine chance for measurable snow on Bay Area peaks, most reliably on Mount Hamilton where a 4–8 inch advisory is in place. For most residents at lower elevations, the event will be felt as heavy rain, gusty winds and occasional hail rather than prolonged snow on streets.
Monitor updates from the National Weather Service and local county offices for timing and road advisories. If you plan to drive into the hills, prepare for winter conditions above roughly 2,500–3,000 feet, bring traction equipment when advised, and avoid unnecessary travel during convective downpours and gusty windows.