Weather
California Winter Weather 2026/27: 10 Steps Before December Snow
Sacramento, CA – A powerful December winter storm could leave California residents facing snow covered mountain highways, frozen plumbing, flooding, dangerous winds and power outages lasting several d
By Rachel Monroe · 2026-11-15T17:54:48.708Z
Sacramento, CA – A powerful December winter storm could leave California residents facing snow covered mountain highways, frozen plumbing, flooding, dangerous winds and power outages lasting several days. With winter 2026/27 approaching, homeowners across Sacramento, Sacramento County, the greater Sacramento metropolitan area and communities throughout California should prepare before heavy Sierra Nevada snowfall, freezing temperatures and powerful Pacific storms threaten their properties.
According to winter safety guidance from the National Weather Service and California Governor's Office of Emergency Services, winter storms can produce significant mountain snowfall, hazardous ice accumulation, damaging winds, flooding and widespread transportation disruptions. Northern California and the Sierra Nevada face substantial snowfall risks, while coastal and southern communities are more likely to experience heavy rain, flooding, mudslides and occasional freezing temperatures in inland valleys.
Here are 10 critical steps California homeowners should take before December winter storms and extreme weather threaten their properties.
1. Inspect Your Roof Before Heavy Snow and Winter Rain Arrive California roofs face different winter hazards depending on elevation and location.
Mountain homes can experience substantial snow loads, while coastal and valley properties may face prolonged heavy rainfall.
Inspect shingles, flashing, gutters, roof drains and attic spaces for existing damage.
Homeowners in Sacramento, Stockton, Modesto and the Bay Area should check aging roofing materials and blocked drainage systems.
Residents in South Lake Tahoe, Truckee, Mammoth Lakes and other Sierra Nevada communities should prepare for repeated snowfall and uneven roof accumulation.
Flat roofed properties require special attention because blocked drains can cause water accumulation and interior damage.
Watch for sagging ceilings, new cracks or unusual structural noises. Never climb onto an icy roof.
Arrange professional snow removal when accumulation threatens structural safety.
2. Protect Water Pipes Before Freezing Temperatures Arrive Frozen pipes can burst and cause extensive interior flooding.
Insulate exposed plumbing in crawl spaces, garages, exterior walls and other unheated spaces.
Disconnect garden hoses, protect outdoor faucets and locate the home's main water shutoff valve.
Homes in the Sierra Nevada, northeastern California and high desert communities face greater exposure to prolonged freezing temperatures.
Residents in Sacramento, Fresno, Bakersfield and other Central Valley communities should also protect vulnerable outdoor plumbing during strong cold outbreaks.
Mountain homeowners should maintain adequate indoor heating during extended absences.
Open cabinet doors beneath vulnerable sinks during extreme cold to improve warm air circulation.
3. Service Your Furnace, Heat Pump or Heating System Before December A heating failure during a California winter storm can quickly become a serious household emergency.
Schedule professional inspections of natural gas furnaces, boilers, heat pumps and other heating equipment.
Replace appropriate filters, verify thermostat operation and check heating fuel supplies.
Residents using propane, fireplaces, pellet stoves or wood burning equipment should arrange inspections and maintain adequate fuel supplies.
Mountain households relying on propane should check tank levels and schedule deliveries before heavy snowfall makes roads difficult to access.
Keep heating exhaust outlets clear of drifting snow.
Never use kitchen ovens, charcoal grills or camping stoves for indoor heating.
4. Prepare for Power Outages Lasting Several Days Heavy snow, powerful winds, falling trees and flooding can damage electrical infrastructure.
Communities across Sacramento, Placer, El Dorado, Nevada and other Northern California counties may experience outages when winter storms damage power lines.
Coastal communities can face additional hazards from strong Pacific storms, while mountain residents may encounter longer restoration times when heavy snowfall blocks access roads.
Keep flashlights, batteries, charged power banks and emergency radios accessible.
Households relying on electrically powered medical equipment should establish backup arrangements.
Portable generators must operate outdoors, at least 20 feet from windows, doors and vents, with exhaust directed away from buildings.
Never operate generators inside garages, basements or enclosed porches.
Residents in isolated mountain areas should identify alternate heating and shelter arrangements before severe weather develops.
5. Build a Winter Storm Emergency Supply Kit Maintain at least three days of emergency supplies, with additional provisions for households in isolated areas.
Store one gallon of drinking water per person daily, nonperishable food, prescription medications, blankets, first aid equipment and pet supplies.
California emergency preparedness officials also encourage households to build larger emergency supply kits when possible because major disasters can interrupt essential services for extended periods.
Residents in Sierra Nevada communities should consider additional provisions if heavy snowfall temporarily closes access roads.
Homes relying on electrically powered private wells should store extra water because pumps may stop functioning during outages.
Keep a manual can opener, flashlights and charging equipment available.
Households in remote mountain and desert communities should prepare for longer travel disruptions when winter storms affect major highways.
6. Prevent Roof Leaks, Ice Dams and Flooding Damage California's winter weather can create multiple water damage hazards.
In mountain communities, melting roof snow can refreeze near colder roof edges, potentially allowing water beneath roofing materials.
In lower elevation communities, heavy rainfall can overwhelm clogged gutters, storm drains and poorly maintained drainage systems.
Inspect attic insulation, seal accessible air leaks and maintain appropriate ventilation.
Clean gutters, inspect downspouts and direct drainage away from foundations where appropriate.
Residents in flood prone areas should review local flood information and consider protective measures before heavy rain develops.
Homeowners near wildfire burn scars should pay particular attention to official debris flow and evacuation warnings.
Avoid attempting dangerous roof repairs during icy or stormy weather.
7. Remove Hazardous Tree Limbs Before Snow and Wind Strike Heavy, wet snow and strong winds can break weakened branches, damaging homes, vehicles and electrical infrastructure.
Inspect trees near roofs, garages, driveways and overhead utility lines.
Arrange professional removal of dead or unstable limbs.
Residents in wooded neighborhoods around Sacramento, Auburn, Placerville, Santa Rosa and the Sierra foothills should pay particular attention to branches overhanging structures.
Mountain properties surrounded by pine and fir trees may face additional hazards from snow laden branches.
Coastal communities should also prepare for falling limbs during strong winter windstorms.
Never approach fallen electrical wires or attempt to remove branches touching power lines.
8. Prepare Vehicles, Mountain Roads and Emergency Access California winter storms can rapidly close mountain highways and create dangerous travel conditions.
Inspect snow shovels, ice scrapers and ice melting supplies before December.
Keep exterior stairways, emergency exits and heating appliance vents accessible.
Drivers should carry blankets, winter clothing, phone chargers, flashlights, food, water and other emergency vehicle supplies.
Monitor conditions along Interstate 80, Interstate 5, Interstate 15 and Interstate 40, as well as U.S. Highways 50, 395 and 101.
Travelers crossing Donner Pass, Echo Summit and other Sierra Nevada routes should prepare for sudden closures, heavy snowfall and chain controls.
California Department of Transportation officials may require tire chains or approved traction equipment on designated mountain routes during hazardous conditions.
Drivers traveling through the Grapevine on Interstate 5 or Cajon Pass on Interstate 15 should monitor winter storm conditions because snow and ice can disrupt these major transportation corridors.
Residents in Southern California mountain communities should prepare for steep roads, heavy snow and limited access during significant storms.
Avoid unnecessary travel during winter storm or blizzard warnings.
9. Test Carbon Monoxide Detectors Before Using Backup Heat Carbon monoxide poisoning becomes a serious winter danger when heating equipment malfunctions or generators are used improperly.
Test smoke and carbon monoxide alarms and replace batteries or devices according to manufacturer instructions.
Heavy snowfall can obstruct vehicle exhaust pipes and heating appliance vents.
Never run a vehicle with its tailpipe blocked by snow.
Keep generator exhaust away from buildings and never use charcoal grills, camping stoves or kitchen ovens for indoor heating.
Residents using fireplaces, wood stoves or other fuel burning heating equipment should ensure chimneys and ventilation systems are properly maintained.
Anyone experiencing symptoms of possible carbon monoxide exposure should move to fresh air immediately and call 911.
10. Establish a Family Winter Emergency Plan Identify where household members can safely shelter if electricity or heating becomes unavailable.
Keep emergency contacts written down and locate warming centers when local officials announce their availability.
Check on older neighbors, residents with disabilities and people living alone.
Monitor National Weather Service forecasts, California Governor's Office of Emergency Services announcements and California Department of Transportation road conditions through QuickMap.
Residents in mountain communities should establish communication plans before heavy snowfall or highway closures restrict travel.
Households in flood prone neighborhoods or areas below wildfire burn scars should know evacuation routes and monitor official warnings.
Families should also identify alternate shelter arrangements if prolonged power outages make their homes unsafe.
Why December Preparation Matters for California Winter 2026/27 Winter weather risks vary considerably across California.
Sacramento, Roseville, Folsom, Elk Grove and the greater Sacramento metropolitan area can experience heavy rainfall, strong winds, localized flooding and occasional freezing temperatures.
San Francisco, Oakland, San Jose and the greater Bay Area face winter hazards from powerful Pacific storms, falling trees, coastal flooding and prolonged rainfall.
Santa Rosa, Napa, Petaluma and the North Bay may encounter strong winds, flooding and hazardous conditions along major transportation corridors.
Stockton, Modesto, Merced and the Central Valley can experience heavy rain, dense fog, localized flooding and occasional freezing temperatures.
Fresno, Visalia, Bakersfield and the southern Central Valley face additional risks from winter storms, flooding and hazardous travel through nearby mountain passes.
Truckee, South Lake Tahoe, Incline area communities on the California side of Lake Tahoe and the northern Sierra Nevada can experience heavy snowfall, prolonged freezing temperatures and major highway closures.
Mammoth Lakes, Bishop and the eastern Sierra face significant mountain snowfall, dangerous wind chills and difficult travel along U.S. Highway 395.
Redding, Chico, Red Bluff and Northern California may encounter heavy rainfall, strong winds, flooding and occasional snow at lower elevations.
Mount Shasta, Weed, Yreka and far Northern California face greater snowfall potential, dangerous travel along Interstate 5 and prolonged freezing temperatures.
Los Angeles, Pasadena, Glendale and Southern California generally experience milder winter temperatures but remain vulnerable to heavy rain, flash flooding, mudslides and damaging winds.
San Bernardino, Big Bear Lake, Lake Arrowhead and the San Bernardino Mountains face substantial snowfall potential, icy roads and temporary mountain highway closures.
Riverside, Ontario, Rancho Cucamonga and the Inland Empire may encounter heavy rain, strong winds and winter travel disruptions through Cajon Pass.
San Diego, Oceanside, Chula Vista and coastal Southern California face greater risks from heavy rain, flash flooding and coastal storms than from snowfall.
Palm Springs, Victorville, Barstow and California's desert communities can experience sharply falling overnight temperatures, strong winds and occasional winter precipitation.
Eureka, Arcata, Crescent City and the North Coast face powerful Pacific storms, heavy rainfall, coastal flooding and falling trees.
California's dramatic differences in elevation and proximity to the Pacific Ocean can create sharply different winter conditions across relatively short distances. A coastal community may experience heavy rain while nearby mountain ranges receive several feet of snow.
Strong atmospheric river storms can also produce major rainfall and flooding impacts even when temperatures remain too warm for snow in populated valleys.
This preparedness guide does not predict a specific December 2026 blizzard, atmospheric river or major winter storm. Significant winter weather remains a recurring seasonal threat, but residents should rely on updated National Weather Service forecasts for actual storm timing and expected impacts.
Waiting until a winter storm warning, flood warning or evacuation notice is issued can leave households scrambling for emergency supplies, backup power, heating fuel and safe travel arrangements.
For California residents, completing these 10 preparations before December storms develop could mean the difference between safely weathering severe winter conditions and facing frozen plumbing, flooding, heating failures, expensive property damage or dangerous emergency travel.