This article explains why a recent Cold Weather Advisory for the North Bay Interior Valleys has expired, what that means for residents, and how it fits into the broader system of National Weather Service (NWS) cold-weather alerts.
Drawing on decades of climate and weather safety work, I’ll clarify the differences between advisories, watches, and warnings. I’ll also outline practical, science-based steps to stay safe during cold spells, even when conditions do not seem extreme.
Cold Weather Advisory Expires, But Chilly Conditions Remain
The NWS office in San Francisco has allowed the Cold Weather Advisory for the North Bay Interior Valleys to expire as temperatures have risen above the official advisory thresholds.
Advisory criteria vary by region, but in this case, the air temperatures and wind chill values are no longer considered hazardous for most people.
Some of the coldest, low-lying or wind-sheltered locations may still dip below 36°F in the early morning hours.
These pockets of cold air can persist even as the broader area warms, due to local factors such as terrain, vegetation, and radiative cooling overnight.
Why Below-36°F Temperatures Still Matter
While a reading just under 36°F might not sound severe, it can be enough to:
Even “seasonably cold” conditions matter because cold-related illnesses often occur at temperatures above freezing, especially when people underestimate the need for proper clothing.
What a Cold Weather Advisory Really Means
A Cold Weather Advisory is issued when temperatures or wind chills are expected to be cold enough to cause discomfort or health effects, but not extreme enough to be immediately life-threatening for most people.
It’s a caution flag, not an emergency alarm.
In advisory-level cold, the NWS stresses simple but effective protective measures.
How to Protect Yourself During Advisory-Level Cold
During a cold weather advisory, the NWS recommends:
These steps are based on well-documented thermoregulation science: heat loss accelerates as air temperature falls and wind speed rises.
Wet clothing dramatically increases conductive and evaporative heat loss.
Extreme Cold Warning: When Staying Inside Becomes Critical
An Extreme Cold Warning is more serious.
It is issued when temperatures or wind chills are cold enough to pose an immediate danger of frostbite or hypothermia, often within minutes for exposed skin.
Under an Extreme Cold Warning, the priority shifts from caution to active risk avoidance.
Key Safety Actions During an Extreme Cold Warning
If going outside is unavoidable during an extreme cold warning, the NWS advises:
These measures reduce convective and radiative heat loss and provide a critical buffer against rapid onset of frostbite, especially in fingers, toes, ears, and the nose.
Extreme Cold Watch: Time to Prepare, Not Panic
An Extreme Cold Watch signals that dangerously cold conditions are possible, but not yet certain.
It is an early alert to prepare infrastructure, travel plans, and households before conditions deteriorate.
Vehicle and Home Preparedness for Severe Cold
In advance of extreme cold, the NWS recommends:
These steps improve your margin of safety if unexpected delays, power outages, or vehicle issues arise during a cold snap.
Cold Weather Alerts and Public Health Protection
All of these products—Cold Weather Advisories, Extreme Cold Watches, and Extreme Cold Warnings—are part of a coordinated NWS effort to protect public health during cold weather events.
Although the North Bay advisory issued earlier has now expired, its purpose remains clear: to prompt timely, science-informed action before conditions become dangerous.
The original information referenced here was published on December 4, 2025, at 3:51 AM.
This reflects the NWS’s continual monitoring and rapid communication of evolving conditions.
By understanding the meaning behind each alert and taking recommended precautions seriously, communities can significantly reduce cold-related injuries and deaths.
This is important even in regions not typically associated with severe winter weather.
Here is the source article for this story: Cold weather advisory issued for North Bay Interior Valleys until Thursday morning