The phrase Academic Year most widely refers to the calendar followed by UC Davis for the undergraduates (quarter system). It can also refer to the schedules followed by the School of Law (semester system) or the Davis Joint Unified School District (earlier start than UC Davis).

UC Davis
School of Law
DJUSD
Start of Year
3rd week of September
3rd week of August
End of August (used to be later)
End of Year
3rd week of June
2nd week of May
2nd Friday in June

The UCD Registrar keeps the online Academic Calendar.