Weather in Rome late May- early June

What is hot for you?
Nobody knows the temperatures for that period in 2023.
For your reference in 2022 on May 31st it was about 20C (68F) at night and 29C (85F) during the day. In 2019 on May 31st it was 11C (52F) at night and 20C (68F) during the day.
I’ve seen anything in between during the last decade.
So I suggest you are ready for anything in that range, or better yet pack a day or two before when a better forecast will be available.

Thanks for the info! Hot for me is 89 degrees which I will probably experience as I move south after leaving Rome for the next 40 days.

You could well hit 89F in Rome in May:

May 2022 weather in Rome, from www.timeanddate.com

The month of May wasn't quite as hot in 2018-2021.

Last time I was there, May 2018, it was sweltering hot! Shorts and tank tops (I am not a fashionista, I was a sweaty older lady!)

I like Weatherspark because it gives probability bands as well as averages. Looks like the odds of it getting above 85F on 31 May is pretty remote. For the lows, remember the lowest temperature is before sunrise and I'm in bed. But they also list temperatures by time of day. Pretty comfortablr by South Texas standards.
Even with bad AC. https://weatherspark.com/s/71779/0/Average-Spring-Weather-in-Rome-Italy#Figures-Temperature.

Ciao amici! Thank you all! Talked to friends in Rome and you are all right! June is summer weather in Rome! Will pack accordingly! Grazie mille