reserve for restaurants for dinner on the 24th and lunch on the 25th
It does get pretty cold and chilly so you want to be covered up. It usually doesn't snow but we've had a few years where we've been surprised to find it snowing in Florence right around the holidays.... usually doesn't stick for long but it does make for pretty scenes right around Christmas.
If you're at all interested in participating in any religious service, the St. James Church is the "American" church in Florence and on the 24th at
6:00 pm there will be Christmas Pageant and Eucharist while at
10:30 pm there will be Christmas Midnight Mass. Everything is in English. See the events calendar here:
http://stjames.it/calendar/event-calendar
On the other hand, you could also go to mass at the Duomo, even if you're not Catholic as it is an interesting experience. In particular, to experience a mass in Gregorian chant you could go on Christmas morning or to vespers in the afternoon, also in Gregorian chant. You can see more about the schedule here:
http://www.duomofirenze.it/attivita/liturgical.htm Ah, all churches will be closed to tourists on Christmas and only be open to those attending the services.
In any case, I'd recommend you contact your hotel and ask about restaurants nearby that they'd recommend for Christmas DAY to find out which will be open in the area - many will be open for lunch but closed for dinner on the 25th. You want to reserve NOW for lunch and plan ahead for dinner... ask at the hotel, since it just might be a question of dining in rather than out for dinner on the 25th. Most restaurants will be open on the 24th, but if you're thinking of having a special dinner out, you'd also do well to reserve ahead of time. There are many good places to eat in Florence but depending on where you're staying, your hotel might have special recommendations for you in the immediate area.
If this is your first time in Florence, you'll enjoy spending time outdoors looking at all the monuments and taking in the view of Ponte Vecchio, Palazzo Vecchio, Piazza della Signoria and the historical center at large. As far as places being closed, only the 25th is the day when most everything is closed. All the other days should be fine - oh if you're here on the 28th, all state museums in Florence are open for free after 7pm as part of the MartedinArte program.
Read more here >>
Hope you enjoy your time in Florence!