Cinque Terre in early September

Weather will be great and always crowded during the day.

hey hey dkg
september is still high season with harvest time, many cruises still sailing (genoa & la spezia ports)
cruisemapper.com
unselect all, click ports and insert name, change to september 2026, the days will tell you how many ships in port & capacity of how many thousands people will be in ports wanting to see same things as you. private/van/bus tours which adds to the daytripping crowds, trains full, restaurants probably crowded, where do you want to go, too bad you couldn't spend a night, buy a R/T train ticket so no waiting in long lines to buys tickets at windows/machines, make sure validate ticket on platform being boarding.
be prepared but do have a great time and enjoy, lots of people dreams to see cinque terre
aloha

dkg,

Early September will still likely be quite busy, especially in the daytime. That's the time of year that I often visit that area. However as the previous post mentioned, it would be a good idea to check the cruise ship schedules for the dates you plan to be there. Hopefully there won't be too many European bus tours landing in the area at that time. I assume you're only planning a day trip?

You can easily travel between the five towns using the local trains, as the travel time is only a few minutes from town-to-town. You might want to buy a pass for the day as that will be easier if you're going to use the trains a lot. Here's some information on the trains - https://www.cinqueterre.eu.com/en/cinque-terre-timetable . You can also check the Trenitalia website for details. If there are cruise ship groups travelling on the trains at the time of your visit, travel by train will be a miserable ordeal (I've experienced that!).

Of the five towns, Monterosso is the largest so it tends to "absorb" crowds a bit better than the others. I wouldn't recommend travel to Vernazza on really crowded days, as crowds can be shoulder-to-shoulder. There are some great restaurants in Monterosso so you could enjoy a fine meal overlooking the ocean before you head back to S.M. Ligure. This restaurant is a favourite of many here (including me) - https://www.cantinadimiky.it/eng/ .

Taking the train is by far the best option. It's direct, fast (41 minutes to Monterosso), and cheap (€9 each way).

Sit on the right-hand side facing forward for the best views on the journey down to le Cinque Terre.