June in Rome, Italy, brings average daily highs of 30°C and overnight lows of 19°C in the 2016–2025 historical record. Allow room to shorten long outdoor plans when the day's forecast is hotter than you want. A schedule with easy breaks and less travelling between stops will give you more choices.
In the record, at least 1 mm of rain or snow falls on 5 of 30 days on average, a daily chance of 16%. Leave some freedom to swap an outdoor day with a sheltered one. There is no need to read the average as a fixed number of lost days; it says nothing about how long rain lasts on each occasion.
The calculated day length, sunrise to sunset, averages about 15 hours. Sunshine averages 14 hours a day. The longer daylight window gives you more choice about when to be outside; it does not mean every part of the day will be sunny. Sunshine is a separate measure, and those hours need not arrive in one uninterrupted stretch.
For a culture-focused visit, group the places you want to see into manageable areas, with time between stops. Check each venue's opening dates before fixing the order. If food is a reason for the trip, leave time around meals rather than filling every gap with another journey. Check the places you choose for current opening hours.
July has an average daily high of 33°C, 3°C higher than June. Its historical rain-day chance is 10%, compared with 16% this month. If your dates are flexible, compare those trade-offs with the kind of days you want. Neither set of averages predicts the conditions of one particular holiday.