Prepositions of time: at, on, in
When we answer a question "when", we mostly use the prepositions at, on, in. There are also cases when we shouldn't put a preposition.
at + time
We use "at" when we speak about the time:
- clock time, including midnight and noon
- with the words "time" and "moment"
- holiday periods
Examples
at six o'clock, at 8:40
at midnight, at noon
at breakfast time, at lunchtime, at dinnertime
at this time, at the same time
at the moment
at Christmas, at Easter
Pay attention
You must remember these two cases when we use "at":
- at night
- at the weekend
on + day
We use "on" when we speak about days and dates:
- with the word "day"
- calendar dates
- in combinations "day of week + time of day"
Examples
on Monday
on Saturdays
on her birthday
on weekdays
on the 15th of May
on Tuesday morning, on Friday night
in + month/season/year
We use "in" with the time of day and all other bigger time periods:
- time of day
- months
- seasons
- decades
- years
- centuries
Examples
in the morning, in the evening
in October, in April
in winter, in summer
in the nineties, in the fifties
in 1995, in 2018
in the nineteenth century
Pay attention
in + time can also mean "this time from now" if we talk about the future
For example
in an hour = an hour from now
in two days = two days from now
in a month = a month from now
No preposition
Sometimes, we don't put any preposition at all:
- in word combinations with this, next, last, every
- with the words today, tomorrow, yesterday and in combinations "tomorrow/yesterday + time of day"
Examples
this morning, this month, this year
next week, next summer, next year
last night, last month, last Thursday
every day, every week, every autumn
today, tomorrow morning, yesterday evening