Hi,
I'm travelling to Florence in March.. Is it possible to take just a day trip to Cinque Terre? Also, would March be a good time to go to Cinque Terre?

Yes, you can take the train early and do it. It's worth more than a day trip, but I know it can be done.

It is definitely possible to make a day trip to the Cinque Terre....but the fastest trip to Monterosso is 2 1/2 hours with one change and most connections are closer to three hours each way.

The weather in March is iffy...it could be beautiful or it could be cold and rainy--no guarantees.

If it were me, I wouldn't take a trip that would involve six hours in transit time for one day.

Possible, but not a good idea: the road to and from is not Italy's best feature (navigating the area around La Spezia is unpleasant); and in March weather, it doesn't sound appealing. It's also one of the most touristed areas in Italy, which you said in another thread you didn't want to do.

The Cinque Terre, however, are as far as I can tell the closest really attractive coastal area to Florence. Your call of course; I wouldn't do it.

Another vote for saving the Cinque Terre for another trip. Too long in transit each way from Florence to be a reasonable daytrip, in my opinion.