I'm seeing some insanely cheap flights to Lisbon for March of next year. My original plan was for us to head there in mid April, but I'm willing to compromise if the weather is decent. How is the weather in March - is it still rainy and coldish or good weather? If it makes a difference, the dates I'm looking at are roughly March 15-30 and the trip would be roughly 2 weeks traveling pretty much south to north.
We were in Spain at that time a few years back. The weather was comfortable, but on the cooler side. Occasionally it rained, but you need to appreciate the geography of the country makes giving a specific weather report difficult. The farther north you go, the cooler the weather and in the hills the same.
I have been further south at the eastern end of the Algarve for your dates twice. We had very mixed weather - a few days when it never stopped raining and some pleasant, warm days - maximum around 20 degrees, but always windy. It’s not beach weather, but good for walking. It’s still cold at night, so no outside dining and you will need a scarf and gloves. Lisbon is likely to be a bit cooler.
On our trip this year from 3/21-4/5 the weather was very temperate. It was a mix of sunny, overcast and rainy days. Mostly it was good weather. We traveled from Lisbon to Porto with many stops between. We had some sunny afternoons where it was comfortable in short sleeves. Most evenings I wore a light sweater and/or light jacket. For us it was a perfect time of year to visit. If you’re doing a moderate to heavy amount of walking with some climbing of steps, etc. it is nice to have somewhat cool weather. Enjoy!
In a normal year (2022 was not the norm), it’s still fairly rainy in March. This year, most of the rain was in April. But, it rarely rains all day and it never is that cold - depending on where you live, it might be a huge improvement.
March avoids the big tourist crowds. As long as you prepare for rain and mid 50’s F weather, it’s a good time to visit.