French Riviera or Amalfi Coast for 1st week of April

You can search weather sites for historic weather averages in different places. I usually use Weatherspark. Neither Nice nor Positano will be what I would consider warm, with day time highs averaging in the mid teens, Celsius, and nightly lows around 10°C. Nice may have a very slight advantage on rainfall probability (18%) , with Positano having about a 5% greater chance of some rain during the day. Chance of a sunny day in either location is about 50/50.

My guess is that the AC will be more impacted by religious rites for Easter week. Both will probably be very crowded with tourists because of the holiday. Nice is a good and efficient place for day-tripping, using the local train. You can visit a couple of towns in a day.

Expect the sea to be quite cold in early April. With likely warm, sunny days, you'll never be more than a short walk from the seashore along the Riviera. That would be my recommendation. There's also more diversity with easy access - markets, great art museums, lots of history.

Transportation for day trips will be a lot easier along the French Riviera, in general, though I don't know what the impact of Holy Week will be in those specific areas.

The climate-summary statistics in the Wikipedia entries for Nice and Salerno indicate Nice is statistically likely to be drier, on average, but very slightly cooler. Given how much weather can vary from week to week and from year to year, I wouldn't consider either of those differences to be significant enough to be a major decision factor. A bigger issue for me would be the amount of your very limited time you might end up spending in a car or bus if you chose the Amalfi Coast. Traffic there is legendary.

Our family and I have a new idea.

We are thinking of spending 2 days in Positano then flying from Napoli to Nice and spending 2 days there before flying back from our original destination.

What do you think about this one?

Thank you

Honestly, this idea sounds like the worst of both worlds. Transportation from Positano to Naples will take a couple of hours minimum and given the uncertainties of travel in the area you'll need to leave well before your flight time. Then flying and getting from Nice airport to Nice sounds like 8+ hours of travel and spending a whole day just on transit for no clear reason.

If you want a relaxing vacation time I would commit to one place for the time. Personally I would choose a city like Nice where there are things do see and do even if the weather is bad and coastal activities if the weather is good. You could do a day trip to Antibes or someplace nearby if you're afraid 4 days is too many for one place.

Deciding is hard when your wish list exceeds your time, but this is always the case. Don't get too caught up in what seems like reasonable plan sitting at home looking at a map and consider what that time will actually be like on the ground when you do it. Whether it is 4 museums in a day or moving constantly between cities temper your expectations and let something go from your list for the sake of your future sanity.

My $.02, people may feel differently,
=Tod