at, in and on (time)

[ at + exact time
in + part of day
on + particular day
at + weekend, public holiday
in + longer period]

  • Exact times
      I usually get up at six o’clock. I’ll meet you at 4.15.
      Phone me at lunch time.
      In informal English, we say What time . . . ?
      (At what time. . . ? is correct, but unusual.)
      What time does your train leave?

  • Parts of the day
    • I work best in the morning.
      three o’clock in the afternoon.
      We usually go out in the evening

    Exception: at night.
    We use on if we say which morning/afternoon/etc we are talking about, or if we describe the morning/afternoon/etc.

      See you on Monday morning
      It was on a cold afternoon in early spring, . . .

  • Days
    • I’ll phone you on Tuesday.
      My birthday’s on March 21st
      They’re having a party on Christmas Day.

    In informal speech we sometimes leave out on. (This is very common in American English.)

      I’m seeing her Sunday morning.

    Note the use of plurals (Sundays, Mondays etc) when we talk about . repeated actions.

      We usually go to see Granny on Sundays.

  • Weekends and public holidays
  • We use at to talk about the whole of the holidays at Christmas, New Year, Easter and Thanksgiving (US).

      Are you going away at Easter?

    We use on to talk about one day of the holiday.

      It happened on Easter Monday.

    British people say at the weekend-, Americans use on.

      What did you do at the weekend?

  • Longer periods
    • It happened in the week after Christmas.
      I was born in March.
      Kent is beautiful in spring.
      He died in 1616.
      Our house was built in the 15th Century.

  • Expressions without preposition
  • Prepositions are not used in expressions of time before next, last, this, one, any, each, every, some, all.

      See you next week. Are you free this morning ?
      Let’s meet one day. Come any time
      I’m at home every evening. We stayed all day

    Prepositions are not used before yesterday, the day before yesterday, tomorrow, the day after tomorrow.

      What are you doing the day after tomorrow ?