SAN FRANCISCO (CBS SF) – A bitter cold weather system settled over the San Francisco Bay Area early Wednesday, plunging temperatures to the high 20s and 30s, threatening early blooming crops and forcing homeless residents to find heat anyway they can.

The National Weather Service has issued frost and freeze warnings in the Bay Area.

READ MORE: One Dead, Three Injured In San Francisco Freeway Homeless Encampment Fire

“This string of cool days and cold nights is potentially hazardous for sensitive populations without adequate sheltering,” the weather service warned. “With cold weather arriving, make sure to remember the four Ps of preparation for people, plants, pets, and pipes…Frost and freeze conditions will kill crops, other sensitive vegetation and possibly damage unprotected outdoor plumbing.”

Amid the cold snap, San Francisco authorities were dealing with an early morning tragedy at a homeless encampment. While the cause of an encampment fire that claimed one life and sent three others to the hospital was still under investigation, temperatures were in the 30s at the time of the blaze.

San Francisco firefighters also contained an early morning, one-alarm blaze in an apartment building on Sacramento Street that erupted behind a wall heater.

Snow flurries were reporting before dawn in the Oakland hills and there was a dusting of snow on the Bay Area’s higher peaks.

With the cold kicking in, the Contra Costa County Fire Protection District warned residents to read the manufacturer’s instructions on their space heaters and furnaces to prevent a carbon monoxide or fire tragedy.

“Make sure it’s well maintained, in the case of space heaters. Don’t use them near — common sense, but don’t use them near any flammable objects, bedding curtains, things like that,” said spokesman Steve Hill. “Any heating device that you use in your home has the potential to emit carbon monoxide if it’s not properly vented. Carbon monoxide is a silent killer.”

In December, a Pittsburg woman died and her family was sickened from carbon monoxide poisoning.

READ MORE: COVID Recovery: Business Opens As Workers Begin Returning To San Francisco Offices

In the Livermore Valley, wineries are keeping a close eye on the weather. Aggressively warm February temperatures did set the vines in motion, but the growth isn’t enough to warrant too much worry.

“I’m really not concerned today. Maybe a couple of weeks from now that could be a different story, but we haven’t gotten bud break yet. We’re close,” said Rhonda Wood of Wood Family Vineyards, where pruning was set late this week or early next week.

A mixed bag of weather was slowly leading to freezing temperatures overnight in Napa. Lows were expected to fall to 32 degrees and visitors were feeling the freeze.

Downtown Napa has been a little quieter than usual. The outdoor dining and wine tasting were practically non existent Tuesday night as visitors opted for the cozy warm indoor spaces.

“I was very surprised.. very chilly. I expect sunshine,” saud Zoe Li of Los Altos.

Lauren Garvey from Napa adds, “It’s too cold, I wish it was summer.”

It was a chilly day but one that brought about a mix of snow and sleet. At Atlas Peak, hail came crashing down on the mountain side but it also hit the lower elevations.

MORE NEWS: Pittsburg Family Memorial Gathering Erupts In Gunfire; One Dead, One Wounded

“As we approached the mountains, we saw some clouds on the horizon and then hail and we were nervous on the way up,” said Raffaela Kenny-Cincotta from San Francisco.

Source: sanfrancisco.cbslocal.com.