In
- used for general dates:
- months
- years
- seasons
- parts of the day (exception: at night)
- used for places:
- cities
- states
- countries
- I was born in September.
- Julio was born in 1998.
- Karla and Alex were born in Mexico.
- Ashley was in Hawaii in the summer.
- The classes were in the afternoon.
- Carlos was in Hermosillo last year.
- They were in Puebla last week.
On
- used for specific dates and days of the week.
- Jack was born on May 12th.
- The party was on July 16th.
- The basketball game was on Saturday.
At
- used for times.
- My sister was born at 7 a.m.
- The meeting was at 3:30 p.m.
* We use “was born” or “were born” to talk about location or time of birth.