Prepositions of time

1. What are prepositions of time?

Prepositions of time tell us when something happens.

Examples:

• in the morning
• on Monday
• at 7 o’clock

2. In / On / At

IN

Use in for:

• months
• years
• seasons
• parts of the day

Form:

• in + month/year/season: in January, in 2025, in summer
• in + the + part of the day: in the morning / in the afternoon / in the evening
• in + duration for a future time: "I’ll see you in two hours."
• in the week / in the 1990s

Sentences

• My birthday is in January.
• I was born in 2000.
• We have a holiday in summer.
• I study English in the evening.

ON

Use on for:

• days
• dates
• a day + part of the day

Sentences

• We have class on Monday.
• She works on Friday morning.
• We visit Grandma on Sunday afternoon.
• Christmas is on 25 December.

Compare: on Monday morning (a particular day) but in the morning (in general).

AT

Use at for:

• exact times
• night
• specific moments
• holiday periods
• the weekend (British English)

Sentences

• We eat dinner at 7 o’clock.
• He studies at night.
• I take a break at noon.
• The movie starts at midnight.
• Let’s meet at the weekend. (more common in BrE)
• Let’s meet on the weekend. (more common in AmE)
• The office is closed at Christmas. / We travel at Easter.

3. Quick comparison

• in → months, years, seasons, parts of the day
• on → days and dates (and day + part of day)
• at → clock times and specific moments

4. Other time words (before, after, during, from … to)

These words also talk about time, but they are different from in/on/at.

• before → earlier than a time
  • Please come before 6 o’clock.
• after → later than a time
  • We eat after work.
• during → inside a period of time
  • She slept during the movie.
• for → length of time
  • She slept for two hours.
• from … to → start and end time
  • I work from 9 a.m. to 5 p.m.

5. Last / Next / Every / This (No Preposition)

These are determiners before time nouns, not prepositions. Do not add in/on/at before them.

Correct vs wrong:

• ✅ next week / ❌ in next week
• ✅ last year / ❌ in last year
• ✅ this morning / ❌ in this morning

Examples:

• Last (the time before now)
  • She finished school last year.
  • We met him last weekend.
• Next (the time after now)
  • My lesson is next Friday.
  • They are traveling next month.
• Every (something that happens regularly)
  • I drink coffee every morning.
  • He plays football every Saturday.
• This (the time happening now or very close to now)
  • I am busy this afternoon.
  • We have a test this week.

6. Common mistakes

Incorrect	Correct
in Monday	on Monday
on morning	in the morning
at January	in January
in 7 o’clock	at 7 o’clock