Palm Springs to Seattle in December
 

The problem with your plan is that if there is snow requiring chains, most rental cars prohibit their use.

https://www.monocounty.org/plan-your...ad-conditions/

I'm totally good in the snow. Lived in Buffalo and Boston for 15 years so I know what snow's like. Its going to be a rental.

You may have to buy your own chains and check your rental contract. I don't know what kind of tires your rental will come with.

If you want to wait out closures, you could stay farther south on 395 than Mammoth. Bishop, Lone Pine have hotels.

No one said you don't know about driving in snow. But it would be more practical/easier if it WASN'T a rental. The problem is tire chains are frequently required . . . and putting chains on a rental vehicle will almost 100% of the time void your insurance. If the SUV has 4wd and snow tires, then that will get you through minor storms w/o chains. Not sure how prevalent it is to find snow tires mounted on rentals in the LA/PS area. But even if the SUV has snow tires, if conditions deteriorate you will need to chain up (and yes, the Highway Patrol, local sheriffs, police do check)

How many days/weeks do you have for this trek? If there is absolutely no snow (unlikely for at least some of the route) the drive will take about 25 hours butts in seats plus stops. If there is snow in the Sierra and/or Cascades, all bets are off.

Your optional plan to take he coast is more likely to be successful.

I have 5 nights to make it up to Seattle. One option is to make it up to a certain point and then hook over to I-5. Maybe not though since I have to go over a pass?

South of Bishop the closest way over is going to be SR 178 to Bakersfield.

You can see Mt Whitney from Lone Pine, no passes that way. I'm not familiar with the passes north of Yosemite.

"Maybe not though since I have to go over a pass?"

If you go north through the mountains you will have to traverse several passes. The highest pass on 395 is over 8,000 feet between Mono Lake and Bridgeport. Then Devil's Gate is about 7500 feet. Siskiyou Pass on I-5 is only about 4500 feet but the road there gets VERY icy and often closes for up to several hours to overnight. Traveling across from 395 to anywhere along I-5 will have you going through very mountainous/rural/possible deep snow regions.

You know about snow in Boston and LOTS of snow in Buffalo -- but maybe not about snow at 7,000 / 8,000.

You'll also have mountains to get through on I-5 going north from CA into OR. If a storm is forecast the coast is your best bet.

A 4WD vehicle isn't going to do you any good in icy conditions, which is just as likely (if not more likely) on the east-of-the-mountains route as encountering snow. This also counts for the I-5 corridor between (roughly) Redding and Roseburg, Oregon, where black ice, not just in the Siskiyous but also on some of the low passes in Oregon, is a constant threat from the evening to mid-morning hours. Add to that the short daylight hours and - to me, anyway - you've got a recipe for an unpleasant drive, during which the stress of driving might take a toll.

But I can understand you'd like to see something new in this drive, so I wonder if you might consider moving quickly north on I-5 to the Sacramento Delta area and maybe take a day to poke around this fascinating part of California. There are a number of communities with terrific history, drives along levees, etc., that wouldn't take you far off a direct-ish route. Delta Narratives | Legacy Communities | Visit the California Delta (visitcadelta.com) . You could also visit some places in the Napa/Sonoma Valleys, like historic and picturesque Sonoma.

The redwoods are spectacular in the winter - misty and mysterious, and the southern Oregon coast is always lovely, even if a storm rolls through. You could stick to the coast through Oregon and up to Cape Disappointment at the mouth of the Columbia River, or you could swing inland from the Oregon coast on beautiful OR Hwy 38 (past the elk at the Dean Creek viewing area) to I-5 near Cottage Grove, then it's a more-or-less sea level zoom up the Willamette Valley to Portland, then home. Here's a map showing the all-101 route - https://goo.gl/maps/mMi2XH8LhjNm56Pi7 - and here's one showing the OR 38 option: https://goo.gl/maps/hEBhWJndRMWVaSEE7

The probability of winter driving conditions (ice, snow) is low on these routes, although I would definitely keep an eye on the weather, especially around the Portland area if you choose that route (the Gorge funnels cold air big time) and there's a nonzero risk of wintry conditions coming down the Grapevine into the central valley, as well as tule fog on the valley floor, which can be quite dangerous. But these are low-probability risks compared to a thousand miles of nervous driving inland. Just my view, anyway.

If the OP is from Buffalo, I'm sure he knows about the hazards of black ice.

Sorry but I-5 is really just too boring to even consider. And then there is the Grapevine.

I think you'll just have to wait for the forecast.

Consider taking the Amtrak Coast Starlight from Los Angeles. The route includes Emeryville, Sacramento, Klamath Falls and Portland on the way to Seattle. No worries about driving a rental car with chains. The Coast Starlight leaves Sacramento about midnight every night and arrives in Klamath Falls early in the morning. I have at times seen US 97 closed between Weed CA and Klamath Falls OR due to snow.

If it were me, I'd leave Palm Springs and head towards the Sequoia National Park / Kings Canyon National Park area and explore that before heading to South Lake Tahoe. You could even do a quick stop in Yosemite (from the West, the East entrance is closed during the winter), before heading to SLT. While I was in the Klamath Falls area, I would take a detour to Crater Lake National Park (its gorgeous in the winter). One of the entrances is closed to Crater Lake during the winter, but one is open year-round.

As others have mentioned, conditions could be harsh on some of those roads in December. Be careful if you go!

tmoos: The OP hasn't been around since the 8th so likely hasn't liked any of our advice . . . But just in case - your route is not really doable in the 5 days he has. Plus 198/Generals Highway are closed and there is no access into SNP. There is some limited access into KC via hwy 180 but the only services / access is as far as Grant Grove Market. Even if roads are clear all the way he wouldn't have enough time for a detour to Crater Lake.