Edited...
We're rethinking a trip and my fly into SD then drive home to outer Portland area. Four nights and just wing the route. Coastline to avoid slabbing it up I5.
Flight to SD is $100 and one way rental is $415...

Original Post:
Headed to LV, then DV for two days Jan 31 - Feb 2. Then driving to San Diego. Are there any places along the route(s) where snow or weather is going to be a factor?

Appreciate the guidance.

Probably not.  But weather is not to be ignored in the area.  There are still road problems from last year in or around Death Valley National Park.    Last year had some well out of the ordinary storms.  Heavy rains and flooding damaged a lot of roads.  The NPS site should be checked for current road conditions in the park.  Check Nevada and California road conditions if things have been really wet, etc., and watch forecasts. There should be plenty of advanced warning on oncoming storm conditions so there shouldn't be any big surprises.  Snow is not typically a problem but between Las Vegas and Barstow there are a couple of higher elevation passes which do get snow.  Cajon Pass, on I15 just north of San Bernardino gets to about 4000 feet and sometimes has snow problems.  Snow and/or heavy rains occur now and then in other parts of the "High Desert" country, too.  Usually not enough to be a big problem but I15 is a very busy highway and probably more than 87% of the travelers aren't experienced in snow. Heavy rains could be an issue at times.

Thank you much! I've been on the NP website and reading about roads issues. We're really on the fence about the trip, hate to cancel last minute due to weather. Been driving for many years and am prepared for winter travel, just not from a rental car.

Have looked at the Cali traffic cams and they are lacking near DV.  I'll keep an eye on the weather forecast but have a backup plan for travel.

Again, thanks.

The chances of having a serious snow problem on any of the I15 passes is pretty limited.  This is a few inches of snow, if any, not feet.  More likely a spin out and accident from someone who drives way too fast for conditions as opposes to a traffic slowed to a stop and sit out the storm.   Very infrequently they'll close Cajon or run escorts .  This is more an every couple of years thing. not several times a year.  Cajon can get rough because it's got heavy commuter traffic, I40 and I15 meet in Barstow then are funneled down to the greater L.A. area. it's also an access route to some of the mountain resort areas and feeds Highway 395 which is a busy north/south Highway to the eastern side of the Sierra and north.  Weekends are bad with Vegas traffic.

If weather looks to be bad, I wouldn't go west out of Death Valley on 190.  That's rugged, remote country and gets to 5000 feet or so.

Thanks again for the info.

We're rethinking a trip and my fly into SD then drive home to outer Portland area. Four nights and just wing the route.
Flight to SD is $100 and one way rental is $415...

I5 from LA to Bakersfield can get snow over the Grapevine pass & Siskiyou pass north of Redding can have weather issues.  Check the weather reports and if it looks questionable take the coast.

Tule fog in the southern Central Valley can be dangerous.   Visibility goes way down, speeds don't.  Multiple vehicles can pile up quick.  I almost always take 101, the coast as mentioned.  Slower but nice.  Or 99 if heading for the mountains.  The high point of I5 heading north is a cattle ranch with a restaurant.

I ran into a real "Tule fog" once.  It was so bad, so dense, even I felt we had to get off the road, and we did.  We could not see anything beyond a couple of feet out beyond out front bumper.  We would come up on cars but could not see their tail lights until we were right on top of them (10-20 feet?).  We had slowed way down, so stopping was not a problem for us but were then worried we'd be hit from behind.  We exited the freeway at the next off ramp and got a motel.  We continued on the next morning, after a good breakfast.  

I believe the ranch is called "Tejon Ranch".

Thanks all. Was worried flights would be $$ due to the latest 737 issues but they remain reasonable. Autoslash.com has a good rate on cars and were were planning to do the coast most of the way. Relatives in Santa Barbara and North of SF.

I'll post a reply with details.

I'm thinking north after I5 splits from 99 north of the Grapevine.  Harris Ranch at I5 and 198 near, sort of, Coalinga.  TBH, I'd be more worried about the potential fog situation than rain or snow on the passes. Just something to be aware of.  I almost never take that route so not sure the best way to get great planning info on the fog.