Northern California Atmospheric River - December 2025

Lodi
Written By Don Bradford

Northern California Atmospheric River & Flood Risk Report

Focus: Sacramento, Elk Grove, Lodi, and Stockton — conditions and forecast as of December 22, 2025

Summary

Northern California is under a prolonged, high-impact atmospheric river pattern bringing several days of heavy rain, high snow levels, and flooding concerns from the Sacramento Valley through the northern San Joaquin Valley.[1][3][7]

Sacramento, Elk Grove, Lodi, and Stockton are all under flood watches, with the greatest concerns for urban flooding, rapid rises on the Cosumnes and Mokelumne Rivers, and levee-stressed Delta areas near Stockton through at least December 26.[3][6][21]

Key Takeaway: The most dangerous window is Tuesday night into Christmas Day, when a second, stronger atmospheric river and rapidly deepening Pacific storm are expected to bring the heaviest rain and strongest winds to the region.[7][46][99]

Storm Overview

Multi-Day Atmospheric River Setup

Northern California is being affected by back-to-back atmospheric rivers drawing deep subtropical moisture toward the coast, a classic “Pineapple Express” setup.[7][21] This has already produced deadly flooding in parts of Northern California and will continue to impact the region through the Christmas holiday week.[1][3][54]

National guidance highlights a long-duration heavy-precipitation event, with repeated waves of moisture leading to saturated soils, rising rivers, and compounding flood risk across the Sacramento and northern San Joaquin Valleys.[17][28]

Two-Wave Pattern

  • First atmospheric river (Dec 20–22): Produced 3–6+ inches of rain near Redding, flash flooding on Interstate 5, and at least one fatality from floodwaters.[1][3][94]
  • Second atmospheric river (Dec 24–26): Forecast to be stronger, tied to a rapidly intensifying Pacific storm that may reach “bomb cyclone” criteria as it nears the coast, bringing heavier rain and stronger winds.[46][95][99]

Snow levels have remained high (roughly 8,000–9,000 feet in the early phase), meaning most precipitation has fallen as rain rather than snow, increasing direct runoff into rivers and low-lying areas.[33][47]

Local Impacts: Sacramento, Elk Grove, Lodi, Stockton

Sacramento

The Sacramento area is under a flood watch, with National Weather Service (NWS) Sacramento highlighting the risk of excessive runoff, urban flooding in low-lying neighborhoods, and rapid responses on small creeks and tributaries.[22][26][31] The broader Sacramento Valley is expected to receive roughly 4–8 inches of total rainfall through Christmas, with locally higher amounts in the foothills.[21][47]

Areas of particular concern include low-lying neighborhoods in South Sacramento, zones near smaller tributaries such as Arcade Creek and Morrison Creek, and locations with poor drainage where storm drains can be overwhelmed by multiple episodes of heavy rain.[40][86]

Elk Grove

Elk Grove, in southern Sacramento County, sits near the Cosumnes River and low-lying agricultural lands that have a history of flooding during strong atmospheric river events.[70][86] Flood watches that include Elk Grove call out the potential for roadway flooding, rapid rises on nearby rivers and creeks, and ponding in neighborhoods with limited drainage capacity.[64][22]

Flood risk data indicate that over a quarter of properties in Elk Grove face some level of flood risk over a 30-year period, underscoring the city’s vulnerability during multi-day heavy rain events like the current pattern.[66]

Lodi

Lodi, in northern San Joaquin County, is also under active flood watches and severe weather alerts associated with the ongoing atmospheric river.[6][74][75] The city can be affected by flows on the Mokelumne River system as well as localized urban flooding when intense rain exceeds storm-drain capacity.[34][37]

Forecasts for the northern San Joaquin Valley indicate about 2–5 inches of rain through Christmas, with heavier local bursts possible during the peak of the second atmospheric river.[21][47]

Stockton

Stockton and surrounding San Joaquin County communities are under flood watches warning of “prolonged periods of rain and gusty winds” that may produce hazardous driving conditions, roadway flooding, and localized ponding.[6][34] The city sits at the edge of the Sacramento–San Joaquin Delta, protected by an extensive but aging levee network that state analyses say is at increasing risk without major investment.[79][82]

County officials have activated emergency protocols, opened sandbag locations, and urged residents to prepare for multiple rounds of heavy rain and potential power outages as soils saturate and waterways rise.[6]

Expected Rainfall Totals Through Dec 26 (Estimate)

Approximate rainfall ranges based on regional forecasts for the Sacramento Valley and northern San Joaquin Valley; actual amounts will vary locally.[21][47]

Areas at Highest Flood Risk

Key River Systems

River / System Primary Concern Communities at Risk
Cosumnes River Fast-rising, largely unregulated river with history of levee failures and overbank flooding during strong atmospheric rivers.[81][86] Wilton, Point Pleasant, rural areas southeast of Elk Grove, stretches near Highway 99.[78][84]
Mokelumne River Rapid rises during heavy rain; potential to overflow banks and impact adjacent agricultural and semi-rural areas.[37][40] Eastern Sacramento County, northern San Joaquin County including areas near Lodi.[34][37]
American River Reservoir-controlled but still capable of high flows requiring increased releases; levee integrity critical through Sacramento.[44][93] Central Sacramento neighborhoods along the American River corridor.[40][93]
San Joaquin River & Delta High flows increase stress on aging levees; levee failure could flood deeply subsided Delta islands and low-lying developed areas.[79][92] Stockton region, Delta communities, nearby agricultural tracts.[79][82]

Highest Concern Zones: Low-lying parts of southeast Sacramento County (Wilton, Point Pleasant), areas along the Cosumnes and Mokelumne Rivers, and Delta-adjacent areas and levee-protected tracts near Stockton carry elevated flood risk during this prolonged event.[70][78][79]

Urban and Local Flooding Hotspots

  • Sacramento: Low-lying neighborhoods in South Sacramento, areas along small creeks and drainage channels, and intersections where storm drains routinely back up in heavy rain.[22][40][86]
  • Elk Grove: Neighborhoods nearer to natural or engineered drainage channels, rural roads near the Cosumnes River corridor, and former floodplain areas.[70][86]
  • Lodi: Urban cores and commercial areas with older stormwater systems, underpasses, and low-lying roadways.[34][74]
  • Stockton: Underpasses, low-lying residential neighborhoods, and roadways near levees and sloughs where heavy rain and high water levels can combine to cause rapid ponding.[6][82]

Historical Context: Cosumnes & Delta Flooding

During the late-December 2022 atmospheric river, levee failures along the Cosumnes River flooded Highway 99, forced rescues, and inundated Wilton and Point Pleasant, illustrating how quickly conditions can deteriorate when strong storms affect this unregulated river.[78][84][86]

State and regional analyses also warn that many Delta levees protecting areas near Stockton are substandard and vulnerable, with repair needs in the billions of dollars, meaning intense multi-day storms like the current sequence present elevated structural risk.[79][92]

Forecast Timeline & Hazards

Rainfall and Storm Evolution

  • Monday, Dec 22: Continued periods of rain as the first atmospheric river gradually weakens, but soils remain saturated and smaller creeks and drainage channels stay elevated.[20][97]
  • Tuesday Night–Wednesday (Dec 24): Arrival of a stronger atmospheric river tied to a rapidly deepening Pacific low, expected to bring the most intense rain and strongest winds to the Sacramento and northern San Joaquin Valleys.[46][95][99]
  • Christmas Day (Dec 25): Heavy rain continues, with the core of the moisture plume shifting south but lingering showers and elevated river levels maintaining flood concerns in the region.[7][47]
  • Friday, Dec 26: Showers taper but many rivers remain high; flood watches extend into Friday afternoon because even light additional rainfall will quickly convert to runoff on saturated soils.[6][20]

NWS outlooks indicate that, through this series of storms, the Sacramento Valley could see around 4–8 inches of rain, while the northern San Joaquin Valley (including Lodi and Stockton) can expect roughly 2–5 inches, with foothill totals significantly higher.[21][47]

Wind and Power Outage Potential

The rapidly deepening Pacific storm associated with the second atmospheric river is expected to produce strong south to southeast winds, with valley gusts potentially reaching 45–55 mph and higher gusts in exposed areas.[46][95] Southerly wind directions and saturated soils will make trees more prone to toppling, raising the risk of power outages and blocked roadways across the Sacramento and Stockton areas.[46][54]

Along the coast and over higher terrain, gusts may be significantly stronger, but even inland communities should plan for scattered to widespread power interruptions around Christmas Eve into Christmas Day.[7][99]

Preparedness Guidance

Household and Property Preparations

  • Clear gutters, downspouts, and storm drains around your property to help reduce local ponding and backup flooding.[6][40]
  • Move valuables from basements and ground-level rooms to higher locations, especially in historically flood-prone zones near rivers, creeks, or low-lying streets.[6]
  • Secure outdoor items and holiday decorations that could become projectiles in strong winds, and trim dead branches where safe to do so.[6][46]
  • Maintain at least 72 hours of food, water, medications, and battery power for each household member in case of flooding or power outages.[6]

Travel and Safety

  • Avoid driving during the heaviest rain, especially Tuesday night into Wednesday, when flooded roads may be difficult to see; never attempt to drive through flooded roadways.[20][46]
  • Monitor local alerts from NWS Sacramento, county emergency services, and Caltrans for road closures and river status updates.[22][32]
  • In flood-prone areas near the Cosumnes, Mokelumne, or Delta levees, be prepared to leave quickly if evacuation orders are issued.[70][79]

San Joaquin County emergency managers recommend residents sign up for alerts at SJReady.org, use county 3-1-1 and public works hotlines to report flooding, and monitor local media and official channels throughout the storm sequence.[6]

References & Resources

Don Bradford
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