It depends entirely on the route you plan to take. High or low?

naimad72.
You may want to start a new thread with your question on driving in the Pyrenees in March and provide us with a little more information on where you would like to visit/stay during your trip, which can easily be made in two days.

there is no way to know today what the exact mountain weather conditions will be.

i doubt you will be able to know until a few days ahead of time due to the possibility of extreme fog or snow dumps.

so just have plan b in place, as you may not feel comfortable driving under adverse conditions.
or you may be lucky and we have a heat wave, ruining all skiing possibilities.. but giving you a great driving experience.

if conditions are bad it is usually best to drive at warmest part of day.

lin is absolutely right. The weather in that part of the country has been totally unpredictable. Follow lin's advise and keep a contingency plan, a southern route, just in case. And the Michelin regional maps of Aragon-Catalunya and Navarra-Rioja-Basque Country are invaluable. I highly recommend them.

We just did 5 days in the french pyrenees and what you do not want is the large people carrier we were "up-graded" to. it was like driving a tank - poor visibility and just as manouverable.
A mid-size car with a bit of oomph will be fine, and much more practical.
Have fun!

I just drove across the Pyrenee's 2 weeks ago and was completely enthralled. I drive agressively and really enjoyed it. My wife on the other hand was grasping anything she could and was wishing she had a brake and steering wheel on her side. I definitely would not try it in March. Although the roads are better than anything in the US, most of the time they are 2 lanes at best and a magnificent view (straight down) for the passenger. We upgraded to a mid-size for extra power. BS

Bob,
Hope your trip went well and that you got to the lighthouses that you wanted to photograph!

I should add that I drove through the Pyrenees on other days that weren't foggy, and it was spectacular, although sometimes the heights made me feel I was driving a plane and not a car. And it can be tiring. Roads on the French side are marginally better than on the Spanish side -- although any time you get off the most direct routes, you find yourself driving some extremely steep switchbacks with no guardrails.

I also heard that in summer the high Pyrenees are subject to intense thunderstorms. The truth is, you are driving in the clouds. If it's not a cloudy day, great. But if you've got *weather* of any sort, it may be more than you're prepared for.

When I was driving in the fog I passed a couple of people who'd pulled over to wait it out. I assumed they lived there! I had a hotel reservation to get to, so I kept driving, figuring at some point (I was descending) I had to get below the cloud. I did, but if it had been snow, I wouldn't dared to continue.

On a perfectly sunny day on the French side, I was going down grades as steep as 8-10 percent. I wouldn't want to do it in anything but dry weather in a rental car.

naimad72,
What is your proposed itinerary or what would you like to see in the Pyrenees between Bilbao and Barcelona? That info will help us to help you. I assume you want to make the drive on the Spanish side.

There are mountain areas that are easily accessible (provided you have no rain or fog) with very good highways, and there are drives that are truly white knuckle. The drives into certain valleys of the Navarran Pyrenees are fairly tame and lower in altitude. The Aragonese Pyrenees in comparison are quite imposing, and there are certain routes in the Catalonian Pyrenees which are extremely serpentine and mean very strenuous driving, such as the stretch between Puigcerdá and Ribes de Freser in the Lleida province.
What spots were you hoping to visit in late March?

I did the stretch between Puigcerdá and Ribes de Freser. That's where I felt like I was flying when I came around some curves. It was stunning, especially since in spring it was so green the very air seemed green. But it was the kind of road where the Spanish put up a sign that indicates the various hazards one might face on the road, and for how many kilometers. On that road, you see signs that indicate rock slides, hairpin turns, cows, oncoming traffic in your lane, floods, slippery roads, etc. and then it says: 30 km. When you get to the end of the 30km, you get another sign with all the same hazards, and it says: 40km

You only want to do one of those every so often on a trip.

Interesting to know that that particular stretch hasn't improved not one bit!

There is nothing wrong with the road. It is extremely well maintained and graded. It just happens to be several thousand feet in the air, and short of blasting a tunnel straight through the mountains, I don't know how it could be made straight. The descent (from the peaks toward Ribes de Freser) was not steep. It was quite gradual.

I got used to the dizzying heights. It is the kind of road one should take if you have time to spare, because I regret not pulling over more often (there are lots of turnouts) to take pictures. Also, it feels safer to go about 30 or 40km per hour, and it's a long stretch. It was an incredibly brilliant, sunny spring day.

For me, the most difficult part of the driving was nearing the valley and its towns. The valley is somewhat populous, so one begins to encounter a lot of traffic, and the speed picks up and people who know the roads expect you to move along rather than gape at the scenery. So I felt under pressure.

Once you've take a few of the high mountain roads, they get addictive. I'm sorry in a way I didn't head all the way up to Andorra, but the day was overcast, so I thought it might be a bust. I've heard there is a road in the Pyrenees not far from San Sebastian with a 16 percent grade! But I cannot imagine trusting the brakes of a rental car for that one!