Rain and snow is returning to Oregon this weekend, and low elevation snow and ice will become possible next week.

Cold weather advisory: Be Aware. A cold weather advisory is issued when seasonably cold air temperatures or wind chill values, but not extremely cold values, are expected or occurring. Be sure you and your loved ones dress appropriately and cover exposed skin when venturing outdoors.

On Saturday at 1:56 a.m. the National Weather Service issued a cold weather advisory valid from 10 p.m. until Sunday 10 a.m. for North Oregon Coast Range Lowlands, Central Oregon Coast Range Lowlands,

But since then, things have dried out. National Weather Service meteorologist Chris Burling said Friday that overall, the Willamette Valley would continue to see cool and foggy weather for at least the next four to five days,

"Light winds and limited air movement will lead to a period of stagnant air conditions," NWS said, warning of "deteriorating air quality for people with respiratory problems" and "visibility one quarter mile or less in dense fog," which "could make driving conditions hazardous."

The National Weather Service has simplified some of its winter weather alerts for Wind Chill and Extreme Cold Warnings.

Forecasters are warning that air pollution may become trapped and adversely affect humans, due to weather conditions in the U.S.

A surface inversion is preventing the normal mixing of air, meaning pollutants will remain trapped at lower altitudes.

Cold Weather Advisories have been put into place across the Pacific Northwest this week, but many might be unaware of the new cold weather terms.

Portland’s air quality is currently comparable to Los Angeles, despite the ongoing wildfires in Southern California.

While the loss of snow is worrisome, experts say that because we had so much snow leading up to January it's not that big of a deal. READ ALSO: Portland's dry spell nears record as rain and possible low elevation snow come into focus For example,

High pressure is keeping weather over the Portland metro area dry and clear with cold overnight temperatures. The cold weather advisory issued overnight and into Sunday morning has lifted, but chilly temperatures are forecast to return tonight to parts of the southern Oregon coast.