Positive Covid as Golden Ticket for April Trip.

If you do a search of the average historic weather in each of your destinations, you will very quickly find that it is unlikely that you would find daily highs above 70°F in any of the places in your first itinerary.

That said, I can't say that I would consider day time highs in the 60's, or even 50s cold. Certainly not if you were properly attired. However Gimmelwald would probably still have a fair amount of snow and will be the coldest of your locations.

Hah! CJean's from Canada. I'm from the southeastern US, and I wouldn't go to any of those places in late March unless I intended to spend virtually all my time knocking off one museum after another. And the only reason I'd consider doing that is the Schengen 90-day limitation that keeps me from spending as much time as I'd like in Europe during the warmer half of the year.

You can find monthly-average climate charts in the Wikipedia entries for most cities. Take a look at the precipitation data as well as the temperatures. And remember that average temperatures are just that: You'd be likely to have days quite a bit colder as well as quite a bit warmer. When deciding how early or late I dare go somewhere, I don't depend on averages or on anecdotal evidence. I dig into the actual, historical, day-by-day weather statistics available on timeanddate.com. I try to check the most recent five years for the month(s) I'm considering. That gives me a better idea of how cold or hot it might get.

Example: Timeanddate.com March 2021 for Amsterdam: Only three days the entire month with a high temperature of over 55F; for most days the high temperature was down in the 40s. https://www.timeanddate.com/weather/netherlands/amsterdam/historic?month=3&year=2021

Wikipedia says there are only two months of the year when even the average high temperature in Amsterdam reaches 70F: July and August; it's under 72F for both months. The time period covered by those Wikipedia averages cuts off in 2010, so today's averages may well be a degree or two higher; weather has gotten wackier.

At the time of year you're proposing to travel, I'd head to southern Spain (Seville, Cordoba, Cadiz, Malaga, Granada and neighboring towns. Granada will be a bit cooler than the rest because of its altitude. Here's what Seville (warmest spot, I think) was like in March 2021: https://www.timeanddate.com/weather/spain/sevilla/historic?month=3&year=2021

Madrid is quite a bit cooler than Andalucia in the winter and early spring, so I wouldn't choose to go there as early you're planning to travel.

You would probably find temps below 70 in all of the places you list at that time of the year. Maybe with Greece being the exception, but not by much. All of the places on your first choice list will likely be cold, cloudy and rainy. Personally, I prefer that weather to heat, but you need to dress accordingly.

Please note that France only accepts European certificates of recovery from Covid.

We flew to the US with recovery letters in December.

You do qualify to fly back, but you may not qualify to fly over to everywhere on your list.

A couple questions come to mind.

As someone mentioned, what you are looking at is only an entry requirement for the US, not European countries. Re you only planning on using this for return, or while traveling?

Are you otherwise vaccinated with a booster?

Basically you would need to look into entry requirements for each country and see if a recovery certificate is allowed in lieu of vaccination.

I guess I do not see this clause as a "Golden Ticket" but a back-up, since a recent infection can create "false positives" for a period of time. As another poster said, everyone is used to the CDC card and looking for tests, to pull out an old test result and a letter from your Doctor is correct, but probably a recipe for confusion. I would definitely have your paperwork as a backup, but plan on complying with the most common requirements.