Bay Area Rainfall Totals: How This Year’s Storms Compare to Historic Deluges
Across the Bay Area, reservoirs are rising, creeks are swollen, and the tally of seasonal rainfall inches closer to—and in some places beyond—historic benchmarks. This winter, a series of atmospheric rivers and Pacific storms have reshaped the region’s hydrology, prompting both relief and concern. With climate change intensifying the extremes between drought and deluge, these totals are more than numbers; they are a measure of risk, resilience, and renewal.
Take San Francisco, where the fiscal year that began last July has already accumulated a rainfall total that puts many recent winters to shame. The opening months of water year 2024, which began October 1, culminated in a parade of storms that pushed the city toward record territory. Then, after a brief lull in midwinter, the atmosphere reloaded, adding billions of gallons to the region’s parched soils and aquifers. From Santa Rosa to San Jose, gauges reported accumulations that rivaled the wettest years of the 21st century.
Since the turn of the millennium, the Bay Area has oscillated between severe drought and extreme precipitation, and the last few years offer a stark example. From 2020 to 2023, much of California suffered through a punishing drought, with reservoirs at record lows and water restrictions in place across the region. This past October, though, the pattern flipped with the arrival of a strong El Niño pattern, ushering in a succession of storms that have drenched the landscape. What began as a promising start to the wet season accelerated in December and January, with multiple atmospheric rivers slamming the coast and pushing rainfall totals to levels not seen in decades.
According to the National Weather Service, several locations in the Bay Area have already surpassed their long-term averages for the season. San Francisco International Airport, typically the benchmark for the region, reported seasonal totals that eclipse the median for this point in the water year. At higher elevations, such as Mount Tamalpais and the Santa Cruz Mountains, gauges recorded even more prodigious amounts, underscoring how topography amplifies the effects of these storm systems. In the South Bay, San Jose and surrounding communities measured rainfall totals not seen since the pivotal winter of 2016–2017, a season that tested the limits of local flood infrastructure.
These numbers are more than abstractions; they translate into real-world impacts for residents, ecosystems, and water managers. After years of drought, the influx of moisture has greened hillsides, refilled reservoirs, and raised groundwater levels across the region. Yet the same deluge that eases scarcity also heightens the risk of landslides, debris flows, and urban flooding, especially in areas scarred by recent wildfires. As one emergency manager in Sonoma County noted, “We went from worrying about dry reservoirs to watching creeks surge overnight. The swing is a reminder that every extreme brings its own set of challenges.”
Municipal utilities have been closely monitoring the rainfall totals, adjusting releases from dams and reservoirs to balance storage with flood control. The San Francisco Public Utilities Commission, which oversees a vast watershed to the west of the city, has shifted from conserving every drop to actively managing flows. “Our reservoirs began the year low, and we were focused on holding onto water,” said a spokesperson for the utility. “Now, with the rainfall totals we’ve seen, our priority is safety and ensuring we don’t overtop our systems during the peak of storm season.”
In the North Bay, where steep slopes funnel runoff into narrow valleys, the stakes are particularly high. During a recent storm, hillside monitoring stations logged hourly rainfall rates that would have been extraordinary even a decade ago. The data, shared with county officials and the National Weather Service, helped inform road closures and evacuation warnings in mountain communities. A district engineer in Marin County remarked that “the intensity we’ve seen in some of these storms is unprecedented in the historical record,” noting that gauges at higher elevations have approached the kind of totals typically reserved for once-in-a-generation events.
Beyond local impacts, this winter’s rainfall totals are feeding into broader regional and statewide assessments. Statewide reservoir storage is well above the historical average for this time of year, and major water bodies such as Shasta and Oroville are holding volumes that would have seemed unthinkable during the depths of the drought. Ecologists are closely watching how these patterns affect salmon runs and riparian habitats, as increased flows can both benefit spawning grounds and scour the delicate gravel beds that young fish need to survive.
Of course, the season is not over. In the Bay Area, winter can stretch into April, and late-season storms often deliver significant precipitation. Past years have seen March nor’easters and April showers add several more inches to the annual tally, sometimes turning a wet winter into a historic one. Long-range climate models suggest that the tendency toward atmospheric river events will continue, with fewer but more intense storms becoming the norm. That pattern underscores the importance of not just measuring rainfall totals, but also planning for the kinds of extremes that can quickly overwhelm aging infrastructure and natural systems.
For residents, the immediate message is one of cautious optimism. Picnic plans may be postponed for a day or two, but the region as a whole is breathing a collective sigh of relief as reservoirs climb and fire risk diminishes. Yet the memory of recent drought years—and the severe impacts they had on agriculture, ecosystems, and communities—serves as a counterbalance to any sense of complacency. As one climate scientist at a Bay Area research institute put it, “We’re reminded again that water is our most dynamic and demanding resource. High rainfall totals are welcome, but they are only part of the equation.”
The months ahead will reveal how this winter compares to the benchmark years that define the region’s climatic memory. For now, Bay Area residents can track each new storm’s contribution to the seasonal total, a tangible measure of the sky’s bounty and the power of the Pacific. In the end, these rainfall totals are not just data points; they are a narrative of resilience, a test of preparedness, and a preview of the challenges and opportunities that a variable climate will continue to bring.
