Yes, the vast majority of Italian trains are equipped with air conditioning, though the reliability varies by the type of service. High-speed trains like the Frecciarossa and Italo have excellent, climate-controlled cabins that are almost always comfortable. Intercity trains also have AC, but it can be less powerful or prone to occasional maintenance issues. The "Regionale" (local) trains are the biggest gamble; while most modern regional fleet cars have functioning AC, older carriages may lack it entirely or feature systems that struggle during Italy's intense 35°C+ summer heat. A quirky cultural note: Italians are often wary of "lo spiffero" (the draft), so you may find the AC set to a milder temperature than in the US, and passengers may object to opening windows even if the air is failing, believing the cross-breeze causes illness.