Italy in August vs July

July is better.

August is hotter though both months can be very hot.
At this late date finding places with AC still available will be hard but probably harder for July since it is closer.

Other problem with August is you add to the international mix much more Italians on vacation in August. The city locals get out of the city in August so any resort areas become packed.

Not sure if closed you mean places already booked so you can not get rooms or actually closed. Nothing closes in either month as for any tourist based business or venue July and August are the most profitable.

It really depends on where in Italy you are going. However a week won't make much of a difference.

August is the peak time for summer vacation spots at the seaside or the mountains or the lakes. July isn't that far behind. However in August the chances of finding "no vacancy" ("completo") signs is slightly higher than July at those types of locations.

The big cities (Florence, Rome, Milan, Naples) have more vacancies in August, because...well because everybody is at the beach. For example between April and October, the number of occupied hotel rooms in Florence is lowest in August for example.
Venice is packed all year around (not sure if you are going there).

In terms of climate, July is the hottest month, not August. However August is the second hottest month, but at the start of the month there is no difference. Basically between mid July and mid August it is the absolute hottest time of the year in Italy, with temperatures easily in the 100s F (high 30s to low 40s centigrade) in many places (coast and mountains at high altitudes are cooler, that's why everybody goes there).

Not much will be closed. Maybe some shops in the big cities, but not really in the city centers where tourists go.

In terms of the weather, you can expect high temperatures throughout the summer (and often in September and October), especially as you travel south. Many Europeans go on vacation in August. Any of the dates you are considering should be fine. We have been in Italy in July and August and did not have any problems with much being closed....perhaps a restaurant or business here and there, but you will have plenty of others from which to choose. Major attractions will certainly be open as usual. My only suggestion is that if you are planning to visit major museums in Milan, Rome, Florence, Venice or Naples, you might want to consider ordering your tickets in advance, since Italy will be filled with tourists/tour groups. I would definitely plan ahead if hoping to see "The Last Supper" in Milan and "David" in Florence. Advance reservations for "The Last Supper" are a must, as admission is limited and timed. Have a great trip!

There will be LOTS of traffic on highways on dates around August 1.

thank you guys so much!! All of this information is super helpful!

One more question- what is Venice like this time of year? And the Cinque Terre? We have heard that it can be quite crowded, but is it even more crowded during July/ August or does everyone try to get to the southern beaches?

Thanks again!

I am in Italy every summer - July through August - some years are very comfortable, last year was extremely hot. I keep telling myself: hot/humid in Italy or hot/humid in New Jersey? I'll take Italy. May I kindly suggest you ask the same question comparing Texas (was born there!) and Italy? The trick when it is hot: drink lots of water, take the afternoons off, move slowly and above all enjoy your vacation!