Evening temperatures in Florence, Tuscany and CT in September

Unless you stay up until 3am you probably won’t need long sleeves at night in Florence (which is in the region of Tuscany).
Tuscany is a region larger than Massachusetts, so I don’t know where you intend to go, but the only places where you will need long sleeves will be at higher altitudes, like Monte Amiata, or similar.
You might need long sleeves at night at the Cinque Terre, as the sea has a cooling effect not present in the interior.
If you plan on taking a jacket instead of a long sleeve sweater make sure it’s a light one. You won’t need a ski jacket anywhere.

Thank you! We'll be visiting Volterra, San Gimignano, Siena and Montepulciano in what I may (incorrectly) consider the Tuscany region.

You can look up historical weather here-this year s Siena Sept 2025
https://www.timeanddate.com/weather/italy/siena/historic?month=9&year=2025

In our experience it just cools down slightly in the evening early September but we would always travel either at least a light long sleeve layer

Hello jshepp, and welcome to the forum,

Another thing to consider is sunset in Tuscany won't be until nearly 8:00pm in early September. I think because of this the heat of the day seems to last well until 5:00 or 6:00pm and generally not until after sunset will the temperatures start to drop off more than a couple of degrees from the high.

Traditionally somewhere in the middle of September the weather breaks and fall suddenly starts. I've been there for it and it is remarkable, but the weather has been less traditional the last couple of years.

You don't say where you're coming from, but if you check the temperatures I think you may be only person worried about being cold in September in Tuscany. Something light with sleeves should be sufficient.

Enjoy Tuscany, it is as beautiful as advertised,
=Tod

Thank you everyone for your replies!