There is no single answer to this. It depends on what climate zone you are in (tropical or temperate) and which hemisphere you are in (north or south).
Making matters more complicated is the fact that many different countries disagree about the season start dates. In Ireland for example, Summer begins on May 1.
Making matters EVEN MORE complicated is the fact that even in a single country like the USA there is considerable disagreement between various agencies about when a season starts. Most American meteorologists believe that Summer begins on June 1, whereas many calendars state that it begins on June 21. (There is no "official" start date to summer in the USA).
So using the most common model of meteorology, here are the seasons (For Northern and Southern hemispheres) and associated months:
- Summer(NH)/Winter(SH): June, July, Aug
- Autumn(NH)/Spring(SH): Sept, Oct, Nov
- Winter(NH)/Summer(SH): Dec, Jan, Feb
- Spring(NH)/Autumn (SH): Mar, Apr, May
The idiot above me does not live in Los Angeles like me. If so they would know all the months come under the wonderful season of summer.