Skeeters? My wife is so susceptible it could be a deal-breaker

Not current, but I have been to Florence twice, once in June and once in September.
Both times, mozzies were not an issue for me outside,, but I did keep the room windows shut at night and had plug in devices to discourage, which mostly worked.

I don't remember mosquitoes being an issue in Florence when I visited a couple times before pandemic. However, I'm from MN and they are our state bird (not really) so I probably wouldn't notice.

It really depends on when you are going. Most mosquitoes come out in the summer when it's warm and moist, and they love standing water. I've been to Florence and Tuscany in May and do not remember seeing mosquitoes, but you just never know. In Minnesota, at least up here in Duluth, they tend to make their appearance in mid-to-late May and stick around until late July,

But we have all these lakes up here with lots of trees and wildlife, so they love our environment. I would imagine that Italy, with its drier Mediterranean climate, is probably not as subject to mosquitoes as the Midwest is here.

Conditions can change in a matter of days so what is happening today is not necessarily what will happen tomorrow. Best to be prepared instead - good repellant (that she knows works for her) and long sleeves and pants - plus keep windows closed. Here's another thread with advice on this topic:
https://community.ricksteves.com/travel-forum/italy/mosquitoes-in-tuscany-18bdbcce-ff8d-479e-bf82-61dc373a9da2

Tuscany is horrendous for the most vicious mozzies I have ever encountered. They love me and I always get bitten to death. Aircon keeps them away so book accommodation with it. However, if it’s a hotel check whether it’s turned on. Many hotels do not turn it on until some specified date. A rental property’s AC should be under your control, but again check. Use lots of repellent - I use picaridin which is as effective as DEET but nicer to use; and don’t sit outside or open windows after dusk if you want to be really careful.

Italy is fab and you should go regardless!

Buggers love me as well I'm afraid. A brimmed hat, collar turnt up, long sleeves, trousers, and a pair of thin cotton gloves pretreated with permethrin spray seem to work as well (and with less health risks) as applying repellant to skin.

May in Florence: made the mistake of leaving the window open overnight. They didn't touch my husband but ate any part of me that wasn't under the covers alive. They didn't bother me at all during the day though, or even much in the evening when we were walking around the center.

Please don't make it a deal-breaker! For Florence, I would suffer through those bites again (but close the window next time)!

Buggers love me as well I'm afraid. A brimmed hat, collar turnt up, long sleeves, trousers, and a pair of thin cotton gloves pretreated with permethrin spray seem to work as well (and with less health risks) as applying repellant to skin.

I do keep a tube of antihistamine salve on hand in case the odd girl (it's the females that bite) manages to poke her proboscis into me somewhere.

I had the same experience as Kate in Florence - opened the window to admire the street scenes below, left it open all night, had a large collection of impressive mosquito bites by morning. Off insect repellant wipes are now a must for me. They work really well, and you can enjoy the amazing Chianti countryside without worry.

Florence sits on a plain that was once a swamp, pretty much until the late XIX and early XX century. The last portion of those marshes were drained in the 1930s by the Fascist regime and that is where the Florence airport is now.

So there are mosquitoes in the area, especially in summer, but you can count on some of them being there even in January. Eat lots of garlic, spray repellant on you if you are in the countryside, and sleep with a fan on you. Mosquitos have a hard time landing on your body with the wind created by a fan.