The Kern County Public Health Department issued a cold weather warning Friday imploring people to stay out of the elements through Monday night because of back-to-back days of freezing and near-freezing temperatures.

Officials advised residents to not only stay inside during the evening but wear layers of loose-fitting, lightweight warm clothes, limit alcohol and caffeine intake that can spur rapid heat loss and see a doctor if they suspect they have hypothermia or frostbite.

The symptoms of those conditions are confusion, dizziness, exhaustion and uncontrolled shivering; gray, white or yellow skin discoloration; and numb or waxy skin.

Public Health also urged people to be prepared by having additional battery-operated lighting, phones and radios -- and making contingencies for loss of heat -- in case the power goes out.

And they advised people to keep on hand adequate supplies of critical, regular medications, both prescription and over-the-counter.

A similar freeze warning from the National Weather Service continued to be in effect until 10 a.m. Monday for the central and southern San Joaquin Valley.

Morning temperatures were expected to range from 24 to 28 degrees in the coldest, rural areas and drop to 28 degrees before sunrise in urban areas including Bakersfield, meteorologists said.

They said pets and some plants also should be protected from the cold.

On a separate but related note, the California Department of Public Health announced Friday that it's seeing an increase in flu cases statewide, but nothing out of the ordinary.

Flu cases usually rise in December and early January and peak in February or March, it said.

The agency didn't have specific numbers of flu cases because those aren't reported to it. But the state does track some trends including flu-related deaths in people younger than 65, said spokesman Corey Egel.

He said there have been four influenza-related deaths reported this season in California.

The agency reminded people that it's not too late to get a flu shot and to follow the typical steps to stay healthy: wash your hands regularly, limit contact with others when you're sick, cover your mouth and nose when you cough, and avoid touching your eyes, nose and mouth.

Kern County Public Health spokeswoman Kim Rodriguez said local flu activity is in line with the state's -- steadily increasing but not abnormally so. No Kern deaths from the flu have been reported to her office, Rodriguez said.

Nationwide, flu is more widespread, but the number of hard-hit states has declined, health officials said Friday.

Flu season started early this winter, and includes a strain that tends to make people sicker. Health officials have forecast a potentially bad flu season, following last year's unusually mild one. The latest numbers, however, hint that the flu season may already have peaked in some spots.

Flu was widespread in 47 states last week, up from 41 the week before, the Centers for Disease Control and Prevention said on Friday. Many cases may be mild. The only states without widespread flu are California, Mississippi and Hawaii.

The hardest hit states fell to 24 from 29, with large numbers of people getting treated for flu-like illness. Dropped off that list were Florida, Arkansas and South Carolina in the South, the first region hit this flu season.

Recent flu reports have included the holidays when some doctor's offices were closed, so it will probably take a couple more weeks to know if the flu has peaked in some places or grown stronger in others, CDC officials said Friday.

-- The Californian and the Associated Press contributed to this story